This page lists all of the errors and inconsistencies I’ve found throughout my 30+ readings of the entire series (I have Stephen Fry’s reading of the books on my phone as an audiobook, to which I listen when I’m resting or trying to fall asleep). I published these as an ebook under a pseudonym, but as the Harry Potter books are a favorite topic of mine and as I continue adding to this list, I’ve decided to create a page for it here on my site.
What Object Was Voldemort Planning to turn into a Horcrux with Harry’s Death?
In The Half-Blood Prince, Dumbledore mentions that Voldemort would have reserved the process of making Horcruxes for particularly significant deaths. He says Harry’s death would have certainly fit the bill. Voldemort is mentioned as wanting to turn only special magical objects into Horcruxes, such as artifacts left by the founders of Hogwarts. This brings up the question of which object Voldemort was planning to turn into a Horcrux with Harry’s death. Is there some important magical artifact hidden in the ruins of the Potter home, or somewhere in Godric’s Hollow, if Voldemort’s curse somehow caused it to fly off into the Halloween night?
There is never a mention of what this object could have been. It seems like Rowling never gave a thought to it.
The Two Flying Hagrids
On the fateful evening of Halloween 1981, Voldemort kills Harry’s parents and tries to kill Harry. This is the evening of October 31st. On November 1st, there is general rejoicing in the Wizarding community as the news of Voldemort’s demise becomes widespread. On the morning of November 1st, Mr. Dursley sees Professor McGonagall in her cat form, reading street addresses and a map. On the evening, the Muggle news mentions strange owl behavior and shooting stars.
Late in the night, Dumbledore arrives to oversee the leaving of Harry at his aunt and uncle’s doorstep. Hagrid arrives on Sirius’s bike, mentioning that Harry fell asleep as they were flying over Bristol.
Hagrid travelled from Godric’s Hollow, a West Country village, to Surrey, close to London, in an arc that passed over Bristol. The distance between the farthest point of the West Country (the coastal village of Sennen Cove) to Bristol is 165 miles, while the distance between Bristol and Surrey is 90 miles. This gives an estimate of about 255 miles that Hagrid had to fly to get Harry to his aunt and uncle’s.
The question is, how long did Hagrid have to fly? If the motorcycle flew at a slow speed of fifty miles an hour, it would have made the journey in five to six hours. Why did Hagrid, then, take an entire 30 hours (from the evening of October 31st to close to midnight November 1st) to arrive?
Hagrid had found Harry soon (an hour or so at most) after the death of Harry’s parents. We know this by the fact that he meets Sirius, who, as Sirius explains in The Prisoner of Azkaban, had left for the Potters’ home as soon as he had found Wormtail’s place empty on Halloween evening. Sirius would have rescued Harry and would have taken him away had Hagrid not gotten to Harry first.
It is clear that in the author’s mind, Hagrid finds Harry in the evening and brings him to his aunt and uncle’s that same night, the journey taking a reasonable 5 hours or so. But, the author also wanted the contradictory fact of giving the Dursleys a day’s warning that strange things were afoot. This leads to two separate timelines, one in which Hagrid takes 5-6 hours to get to the Dursleys, another in which he takes about 30 hours, perhaps traversing the southern English countryside by the scenic way of Scotland.
The Winking Snake
When Harry is allowed to tag along on the zoo trip on Dudley’s birthday, the boa constrictor is mentioned as winking at Harry. Snakes don’t have eyelids, so they cannot blink or wink.
The book mentions Harry’s birthday being on a Tuesday. We already know that Harry’s birthday is on July 31st, and we know that the year is 1991. In the real world, July 31st, 1991 is actually a Wednesday, not a Tuesday. Rowling makes various other weekday-to-date mismatch errors throughout the books, I haven’t mentioned them all, as it got boring after a while.
Rowling mentions the air getting colder as Harry, Hagrid and Griphook go deeper under London through the Gringott’s subterranean railroad. In reality, the air should have gotten warmer as they went deeper into the Earth. Miners working deep underground are at risk of heat stroke, since the closer one gets to the center of the Earth, the closer they are getting to the molten stuff that volcanic lava is made of.
Narcissa’s Wand Shopping
Malfoy mentions his mother looking for wands for him. Since the relationship between a wizard and his wand is mentioned as being very important, shouldn’t Malfoy be with her to look at and try on the wands? There are various possible explanations for why his mother might be looking at wands for him. Maybe she was looking to select a few interesting ones until Malfoy could come around to try them on.
Gryffindor’s Dark Wizards
Hagrid says that there is not a single witch or wizard who went to the Dark Side except that they were in Slytherin. Yet at that time it was general knowledge that Sirius Black, a Gryffindor, had gone to the Dark Side and had murdered 13 people, besides aiding in the murder of Harry’s parents.
This can be explained away by saying that Hagrid was simply exaggerating.
Unicorn Horn Pricing
In chapter 5, unicorn horns are mentioned as costing 21 galleons each. In The Half-Blood Prince, a single unicorn tail hair is mentioned as costing 10 galleons. As unicorn horns are much rarer than unicorn hairs (since a unicorn has only one horn but possibly hundreds, if not thousands, of tail hairs), a unicorn horn should have cost much more than a hair. In fact, a reasonable price for a unicorn horn may be 1000 galleons.
Since beside supply, demand also affects pricing, one could say that there might be a low demand for unicorn horns, causing the low price.
Mrs. Weasley’s Amnesia
At the first King’s Cross Station scene of the series, Mrs. Weasley is seen asking her children which platform number the train is on, even though the same platform (9 & ¾) has been in use for at least over twenty years.
We know this due to the fact that in The Deathly Hallows, when Harry watches Snape’s memories in the Pensieve, he sees a scene with the young Severus and Lily at platform 9 & ¾.
Additionally, since Mrs. Weasley has sent most of her children through the same platform to Hogwarts (Percy is in his third year, the twins are in their second year), she would have seen the platform number enough times to memorize its number. Her sons Bill and Charlie both graduated from Hogwarts within the last twenty years, giving her many chances year after year to see the platform number.
Therefore it is inconsistent that she should wonder about the platform number, even if the platform number had changed since she herself graduated from Hogwarts.
Sir Nicholas’ Death Date
In earlier editions (including the audiobook with Stephen Fry’s voice), Sir Nicholas de Mimsy-Porpington says he hadn’t eaten in nearly 400 years. In the next book, Sir Nicholas is celebrating his 500th deathday. This would suggest that he had continued to eat for 99 years after his death.
The Imbalance of Quidditch
Each goal in Quidditch earns the scorer ten points, while catching the snitch earns 150 points. This practically turns every player into a menial worker except for the seeker, who is turned into a super-celebrity at everyone else’s expense.
The imbalance of Quidditch also allows the players to break the rules with impunity, since even if they receive a penalty, only a measly 10 points would be at stake. Players have a very strong incentive to sabotage the Seeker of the other team, since if they commit a foul while preventing him or her from getting the Snitch, they only risk losing 10 points from the penalty, while preventing the other team from scoring 150 points and winning the game.
Voldemort’s Miraculous Memory
People who suffer from amnesia keep their souls (as far as we know), but lose their brains. How did Voldemort keep his memories when his brain was destroyed by the rebounded curse that gave Harry the scar?
Losing his brain would have been the same as suffering total amnesia, yet for some unknown reason he is able to keep his memories. The Tom Riddle that comes out of the diary in The Chamber of Secrets also has his memories, even though he doesn’t have a brain. In this case his having memories is more believable since the diary could have acted as a memory store for him.
Voldemort’s main soul, which was nothing more than “mere shadow and vapor” as he himself describes it, would have had no mechanism that we know of of retaining memory. One can argue that having Horcruxes gives one the ability to preserve memories after brain loss, but this concept should have been addressed in the books.
As things stand, we have no way of explaining Voldemort’s miraculous retention of all of his memories and talents.
Something as simple as a badly performed Imperius curse can addle a person’s brain (as mentioned in The Half-Blood Prince regarding Herbert Chorley, Junior Minister of the Muggles), yet something that totally destroys Voldemort’s brain leaves all of his faculties intact.
Troll in the Dungeons
Once Quirrel cries troll during the Halloween feast, Dumbledore sends each house back to their dormitories. This means that the Slytherins were sent to the dungeons, exactly where Quirrel had said the troll was.
In the sixth stage of the protection scheme put in place to safeguard the Philosopher’s Stone, Harry and Hermione have to solve a logical puzzle to find out which potion to drink. The potion that Harry drinks to go ahead into the seventh chamber is described as extremely small, with there barely being enough for one person.
Quirrel presumably had to use the same potion to go into the seventh chamber. Why did he not drink the entire potion? And if he had only drunk half of it, why couldn’t Harry and Hermione see that that particular potion had less potion in it that it should?
And why did Quirrel leave the potions table in such pristine condition? We could say he did it to prevent any followers from thinking he had been in the chamber, but this doesn’t serve any purpose, since the knocked-out troll in chamber 5 would have been ample evidence that somebody was trying to break through.
The only explanation is that Quirrel suffered from a form of OCD that made him put the stopper back onto the potion vial, put the potion back into its exact position on the table, and perhaps use a spell to refill the vial. If he was in a hurry to get to the stone, which we know he was, it would have been more logical for him to drink the potion and immediately run toward the exit, instead of wasting precious time restoring the potion to its original state.
Additionally, since Harry and Hermione knew that antagonist had been there before them, why didn’t they wonder at all which potion they had drunk, which presumably allowed them to successfully exit the chamber into the next one?
It is of course possible that there was some form of charm in the chamber that restored it to its original state after someone successfully exited it.
Dumbledore says “we must have crossed in mid-air”, referring to the fact that he had come back before receiving Hermione’s owl asking him to come back. Yet Hermione mentions running into Dumbledore on her way to send the owl. Therefore Dumbledore’s statement is incorrect.
Aunt Petunia’s Amnesia
On his way back to the Dursley’s, Harry says he is going to have a lot of fun with Dudley that summer since the Dursleys don’t know he is not allowed to use magic outside of school. But since Petunia grew up with a witch sister, she should have remembered quite easily that witches and wizards can’t use magic outside of school. The law that prohibits the use of magic outside of school for underage wizards was written in 1875, as mentioned by Mafalda Hopkirk in her warning letter to Harry, thus the law would have applied to Lily and Harry both.
The Basilisk comes out of Moaning Myrtle’s bathroom at least four times, and Ginny presumably had to be in the bathroom to let it out (as Myrtle mentions hearing a boy’s voice when she herself was killed by the Basilisk in that same bathroom). How did Myrtle never see the Basilisk or Ginny in her bathroom? The only time she interacts with Ginny is when Ginny throws Tom Riddle’s diary through her into a toilet.
The Dursleys Use Owl Post?
On Christmas morning, Hedwig brings Harry a letter from the Dursleys containing a toothpick and a note asking Harry to find out if he can stay at Hogwarts during the summer. The Dursleys are depicted as hating and fearing anything to do with the wizarding community, so how on earth did they stoop to sending messages to Harry by owl?
At the beginning of the The Goblet of Fire, Mr. Dursley is barely able to control his temper when Harry mentions owl post in passing. Their sending something by owl is completely out of character for them.
Additionally, Harry aunt and uncle send him Christmas “presents” in his first and fourth year also. How did they send the presents to Hogwarts? While The Chamber of Secrets mentions owl post, the other two books do not mention the mailing method. Did they just write “Hogwarts” (a word that Harry uncle couldn’t bear to hear) on the envelope and assume the post would take it to Harry, perhaps the way Petunia sent her letter to Dumbledore all those years ago?
After Lockhart debones Harry’s right arm, he spends the night in the hospital wing. Dobby gives him a visit during the night, which ends when they both hear the sounds of people approaching the hospital wing. At this time Harry has been holding onto Dobby’s wrist for a few minutes, to prevent Dobby from beating himself up as he is wont to do when he says anything he considers secret or inappropriate. Dobby says that he has to go and disappears with a loud crack, and Harry’s fist is left clenching on thin air.
Rowling invents Side-Along Apparition in The Half-Blood Prince, which allows a wizard or elf to hold on to a person and take them somewhere else using apparition. In The Deathly Hallows, Kreacher, a house-elf, uses it to bring Mundungus to No. 12, Grimmauld Place and Dobby himself uses it to rescue Harry and his friends from Malfoy Manner. In the same book, Yaxley holds onto Hermione when she disapparates herself and her friends out of the Ministry of Magic, which shows that it is possible to force yourself to be apparated by someone else if you hold on to them.
Therefore it is an inconsistency that Harry can hold on tight to Dobby’s wrist while Dobby disapparates without being disapparated himself.
Classes on a Sunday
On February 14, 1993, Harry is stopped by one of Lockhart’s dwarves to sing him his musical Valentine’s message while he is on his way to charms. That date happens to be a Sunday and there should have been no classes. A large crowd of students is mentioned as being present at the school, showing that the date was a normal school day. Clearly, Rowling didn’t realize that date was a Sunday.
When Hermione finds out what Slytherin’s monster is, she tears the page that mentions the monster from the library book that mentions it. This is very un-Hermionish behavior. The books describe her as someone who loves books and who carefully follows the rules, yet in this case she removes a very important reference article from a book that might have been the only one that could have shed light on solving the Chamber crisis.
Couldn’t she have simply checked the book out from the library? Since she had access to the book, she had the right to also check it out, as shown when she is able to even check a book out from the Restricted Section. Therefore even if the book had belonged to the Restricted Section, if she had acquired the right to view it, she would have also had the right to take it out of the library.
The only explanation is that she was in such hurry that she couldn’t justify the five minutes it would have taken to check the book out.
Safety by the Basilisk
On the day that Hermione and another girl are petrified by the Basilisk, Harry is outside on the Quidditch pitch, glad that the castle is deserted and thus no attacks can happen. But once the attack happens, professor McGonagall comes into the pitch and asks everyone to go back inside—where the Basilisk is, for their own safety.
Tom Riddle makes fun of Hagrid, mentioning how he tried to raise werewolf cubs under his bed. Since werewolves are human for three weeks out of four, Hagrid would have had three babies, or at least small children, to raise three weeks a month, a situation that would have been completely untenable for a student, and impossible to hide without serious abuse and neglect of the children. It seems that Rowling wrote this remark before she had clarified her own ideas regarding the nature of werewolves.
After Harry’s efforts clears Hagrid’s name, why isn’t his right to carry a wand restored to him? The Ministry finds out that it made a mistake when it broke Hagrid’s wand, yet it makes no effort to restore the all-important right of wand carrying to him, and Hagrid never complains.
Perhaps the right to carry a wand was only granted to people who successfully finished their magical education, and since Hagrid was expelled from Hogwarts, he forever lost the right to carry one. This makes the law extremely unfair, as anyone who misses their education for one reason or another forever loses the right to carry their all-important wand.
The Creepy Mirror
When Harry stays at the Leaky Cauldron after blowing up his aunt, his room is described as containing a mirror that was intelligent enough to tell Harry he was fighting a losing battle trying to fix his unruly hair. Why wasn’t Harry creeped out that something intelligent and observant was in the room, probably seeing his every action, or at least seeing everything he did within sight of the mirror? Since a mirror reflects light not just from directly ahead, but from all directions, the mirror would have presumably had close to a 180 degree view of the room. In other words, it would have had a perfect view of the entire room, only lacking a view of the area behind it, which was occupied by the wall (assuming magical mirrors see through their reflective part, which is the standard in magical fairytales).
Having a talking mirror in your room is the same as having a camera that observes everything you do. It is extremely off-putting, therefore the book should have provided a reason why people didn’t find them so. Mr. Weasley warns Ginny to never trust a magical object that can think for itself if she couldn’t see where it kept its brain. Wasn’t the mirror just such an object? If not, why?
Mr. Weasley’s Error
On the night before Harry return to Hogwarts, he hears Mr. and Mrs. Weasley having a loud argument about him. At one point Mr. Weasley mentions that Harry and Ron have already ended up in the Forbidden Forest twice, expressing his worry regarding his son’s and Harry’s habit of putting themselves in dangerous situations. The truth is that Ron has only ended up in the forest once (in his second year, on the night that he and Harry pay a visit to Aragog). It is only Harry who has ended up in the forest twice, in his first year when the geniuses at Hogwarts decide that it is a good idea to send students out in the middle of the night into a dangerous forest to find out what could be killing unicorns, and in his second year when he visits Aragog with Ron.
The Walking Trunks
Harry, Ron and Hermione go inside the Hogwarts Express to find a place to put their luggage. Then they come out to say goodbye to Mr. and Mrs. Weasley. Then they go back inside and for some reason have to find yet another compartment, at the end of the train (where professor Lupin is sleeping) to stay, since all the other compartments are full. Harry’s luggage happens to be in the compartment with them, as they hear the Sneakoscope go off.
If they had gone back to the same compartment as before, there would have been no need for them to look for compartments after re-boarding the train. And if they were in a different compartment, as the book suggests, Harry’s trunk shouldn’t have been there with them.
Lupin Out in the Moonlight
Harry and his friends board the Hogwarts Express on September 1st, 1993, to go back to Hogwarts. They are accompanied by Professor Lupin on this trip, who is sleeping, or knocked out at any rate, in their particular compartment. It just so happens that September 1st, 1993 was the night of a full moon, therefore Professor Lupin should have been nowhere near humans at such a time, since he was yet to benefit from Professor Snape’s potions.
The Rarity of Time-Turners
With the use of the Time-Turner, Hermione is able to take 12 classes in her third year. Eventually she drops Muggle Studies and Divination, so that she ends up receiving 9 Outstandings and 1 Exceeds Expectations in Defense Against the Dark Arts in her O.W.Ls.
It so happens that Ron mentions Percy receiving 12 O.W.Ls, which he couldn’t have done without a Time-Turner of himself, since the Study of Ancient Runes and Charms classes are held at the same time on Friday mornings, and Divination, Muggle Studies and Ancient Runes all happen at the same time on Wednesday mornings.
It is possible that during Percy’s years the classes were all so arranged that he could take them without the need for Time-Turners. However, it is clear from Rowling’s tone regarding Hermione’s efforts that it is unheard of for a student to take 12 classes, therefore his brother’s 12 O.W.Ls houldn’t be something that Ron can mention so flippantly.
Barty Crouch, Sr. also mentions his son getting 12 O.W.Ls.
After Malfoy is attacked by Buckbeak, Slytherin is able to skip a match, letting Hufflepuff take on Gryffindor, using Malfoy’s injury as an excuse. How was Malfoy able to pull this off when throughout the books no other game is ever delayed due to injury? Harry suffers much worse injuries, yet there is never a suggestion that his injuries could in any way affect game schedules.
The Oblivious Twins
The Twins acquired the Marauder’s Map on their first year. Ron comes to Hogwarts in the Twins’ second year, bringing Scabbers with him. Since Scabbers showed up as “Peter Pettigrew” on the Marauder’s Map, the Twins should have had ample opportunity to see him on it.
The Potters use a Fidelius Charm to hide from Voldemort. They want Sirius to be the Secret-Keeper, but at the last minute Sirius choose to make Pettigrew Secret-Keeper, who as we know betrayed his friends to Voldemort. The question is, why wasn’t one of the Potters made Secret-Keeper? It would have been a lot safer to do this, as in this case they wouldn’t have had to put their trust in someone else. It is mentioned that Dumbledore offered to become Secret-Keeper himself.
We know that it would have been almost certainly possible for one of the Potters to become Secret-Keeper as in The Order of the Phoenix Dumbledore is the Secret-Keeper of No. 12 Grimmauld Place and is able to visit the house, and no inconvenience or limitation is mentioned on his ability to make use of the house.
In The Prisoner of Azkaban, it is implicitly assumed that the Potters had to have a Secret-Keeper that wasn’t one of them, but using the logic from the The Order of the Phoenix, they were under no such mandate.
Snape’s Unusual Strangeness
Malfoy witnesses Harry’s head at Hogsmeade and runs back to Hogwarts to tell Snape. Snape gets a hold of Harry and takes him to his office. He then calls Lupin to ask him about the Marauder’s Map, since he is the Hogwarts Defense Against the Dark Arts teacher and is supposed to be an expert in such objects. Snape should have known that no matter how much Lupin knew, he himself probably knew much more about the Dark Arts, having been obsessed with them since his early teenage years, and having spent years around Death Eaters.
It is possible that he called Lupin hoping to get corroboration for his theory that Harry had a dangerous object in his possession. But he should have remembered that Lupin was a close friend of Harry’s dad, and that he might be prepared to defend Harry regardless of the truth, which is in fact what happened.
On the memorable occasion that Snape substitutes for Lupin, he tells Hermione it is the second time she has spoken out of turn, taking five points from Gryffindor. It is actually the third time. The first time is when she enumerates the topics they have taken so far (boggarts, Red Caps, kappas, and grindylows), the second time is when she points out to Snape that they are not supposed to study Werewolves yet, and the third time is when she can’t stop herself from counting the ways one can recognize a werewolf.
The Discontinuous Tether
On the day of Buckbeak’s appeal-execution, Buckbeak is mentioned as being tied to a tree. But when Harry and Hermione go back in time, Buckbeak is tied to a fence.
When Harry, Ron, Hermione, Lupin, Sirius and Pettigrew are having their cosy chat in the Shrieking Shack, Sirius mentions that Voldemort has been in hiding for fifteen years, when the truth is that Voldemort has been in hiding for almost exactly the same length of time that Sirius has been in prison and Pettigrew in hiding, which is twelve years.
The Seeker Keeper
In chapter 15 (“The Quidditch Final”), Katie is mentioned as putting another penalty past the Slytherin Seeker (who incidentally happens to be Draco Malfoy), when what the author must have meant was Keeper. It is possible that this error has been corrected in later editions.
Owl Post Again
How did owls find the people the messages were addressed to? Why couldn’t the Ministry of Magic use them to find Sirius? All they would have needed to do was send him a message by owl, then follow the bird.
Sirius is able to send Harry a letter by (the yet unnamed) Pigwidgeon, who is able to find Harry while he is onboard of the Hogwarts Express back to London.
In The Goblet of Fire, we learn that owls are not special. Sirius sends Harry a message by a large tropical bird. Do all birds have this magical power of finding their addressees without being given their addresses, or is there some sort of spell required to give them said power? This is never, well, addressed in the books.
On the night they meet, Harry expresses surprise that people can find Slughorn’s address to send him things, when Slughorn proudly refers to the number of contacts he has in the magical world. Why should he find any surprise in this when he himself kept in easy and regular contact with Sirius Black, a much more hunted man than Slughorn?
Security at the Riddle House
Frank Bryce, the muggle caretaker of the Riddle House in Little Hangleton, finds out that Voldemort and Wormtail are there in the house by seeing the flickering light in one of the abandoned house’s windows. Why didn’t Voldemort and Wormtail not use a few muggle-repelling and other security charms so that it wouldn’t be obvious that there were people in the house? It is a serious security risk to take up residence in a house that is supposed to be abandoned without using any safety measures when Voldemort knows that news of his or Wormtail’s presence at the house would be highly dangerous to his cause.
In chapter 2 (“The Scar”), Rowling mentions that Harry had found out only two months ago that Sirius was his godfather. In reality, Harry finds out about Sirius being his godfather about a week before Christmas of his third year (when he overhears the Minister for Magic and a few Hogwarts teachers having a drink at the Three Broomsticks), which means he has known about Sirius being his godfather for about seven months.
Dudley’s Magical PlayStation
On his birthday, in his letter to Sirius, Harry mentions Dudley throwing his PlayStation out of the window. It so happens that the first ever PlayStation was released over four months later in Japan (on December 3, 1994), and in September 1995 in Europe, therefore Dudley shouldn’t have had a PlayStation.
The Glitch in the Matrix at the Quidditch World Cup
This is one of the weirdest errors in the books. When the Ministry wizards are interrogating Winky after finding her with a wand in her hands, Mr. Crouch shouts at Mr. Diggory, saying Diggory is suggesting he teaches his elfs how to conjure Dark Marks. Diggory says that is not what he meant at all, but Crouch says if he accuses his elf, he accuses him. Crouch then asks the rhetorical question, “Where else would she have learned to conjure it?” In reply, Mr. Diggory says the elf might have picked it up (learned how to conjure a Dark Mark) anywhere.
Here is where the glitch starts. Mr. Weasley says “Precisely, Amos, she might have picked it up anywhere”, after which he proceeds to ask Winky about where she picked up the wand. In other words, the sense of “picked it up” changes from “learning to conjure a Dark Mark” to “picking up a wand from the ground”.
A possible explanation is that J.K. Rowling took a break from writing right before Mr. Weasley speaks, so that when she comes back to resume writing, she forgets that the picking up they are talking about is about learning, not about picking up wands from the ground.
Dumbledore’s Highly Inaccurate Statement
Dumbledore says that he and the Ministry have worked hard to ensure that no Triwizard champion finds himself or herself in mortal danger during any of the tasks. This is pretty much tantamount to a lie, since it turns out that the tasks are actually as mortal as anyone could imagine; the dragon in the first task could have easily incinerated one of the champions, for example.
A Failure of Imagination
It is mentioned that entering one’s name in the Goblet of Fire represents entering into a binding magical contract. Since the Goblet of Fire goes out after the champions are chosen and does not come back to life until the next tournament, names of new champions cannot be thrown into it to ensure each school has two champions (after Hogwarts gets its second champion in Harry Potter). Rowling seems to think that these two facts can explain why the other houses cannot enter new champions into the tournament, but they do not. Couldn’t each school choose a new champion using a different method, and enter them into the tournament? As far as we know, the Goblet’s only jobs are to choose a champion and to force them to go through with the tournament. This does not preclude the possibility of entering new champions into the tournament and forcing them to finish the tournament using another form of magical contract.
In chapter 14 (“The Unforgivable Curses”), the author says that Snape has failed to get the Defense Against the Dark Arts job for the fourth year running. It is true that he has failed to get the job for the fourth year running since Harry came to Hogwarts, but he has actually failed to get it for over a decade. In The Order of the Phoenix, Snape tells Umbridge that he has been a teacher for fourteen years, and that he has been applying for the DADA job since he first joined the school.
A Year of Education Lost
Not exactly an error, but the Beauxbatons and Durmstrang students who came to Hogwarts would lost a whole year of education, and there is no mention of them taking part in Hogwarts lessons. There should have been some mention of how this was going to be dealt with once they went back home.
Karkaroff makes fun of Mad-Eye, saying that he mistook a carriage clock for a basilisk egg. In The Chamber of Secrets, the page that Hermione ripped out of a library book, and that gave details on basilisks, mentions that a basilisk is born of a chicken egg hatched beneath a toad. Therefore there is no such thing as a basilisk egg. Maybe Karkaroff didn’t know much about basilisks, or the textbook was wrong, or Moody didn’t know much about basilisks and thought they have eggs.
Of course, it is also possible that basilisks can reproduce, though the way the books talk about them suggests that they are specially created monsters.
Floo Network Security
Sirius Black, a wizard wanted for murder, can break into a wizarding home to connect himself to the Floo Network and chat with Harry using the fire in the Gryffindor common room. Earlier in the book, Molly Weasley passes some buttered toast to Amos Digory using the Floo Network when his head is in the fire in the Burrow’s kitchen. It appears that Floo Network can be used for conversing with people, and for going to the place specificed (both of which use Floo powder, as Harry has to use Floo powder to use Umbridge’s fire to talk to Sirius and Lupin). What all of this means is that anyone coud have broken into the Gryffindor common room at any time using the Floo Network. There is nothing preventing a random wizard from using a random fireplace to get inside the common room at 3 AM if he feels like it.
The same applies to the fire in the kitchen of No. 12 Grimmauld Place. Harry can use Umbridge’s fire to connect to it and potentially get inside it without any preparation or negotiation with the inhabitants.
There are ways to solve this security issue, but the books provide no clue to readers as to why the above scenarios would not be possible. One could say that certain fires could be set up to prevent people from using them to get inside a place, but that would still enable random people to use the fires to spy on the inhabitants, as Sirius does in Harry’s fifth year, popping into the fire every hour while he sought a chance to speak to Harry and his friends. But maybe this spying is only possible with certain fires, for example if the people at the target gave permission to the initiators to use the fire in such a manner. Maybe Dumbledore set up a special link between No. 12 Grimmauld Place and Hogwarts, except that the Floo Network is owned and controlled by the Ministry of Magic, and it is highly unlikely that Dumbledore could have done such a thing, what with the Ministry wanting to get Dumbledore for something, anything, and with the fact that No. 12 Grimmauld Place happened to be Dumbledore’s secret headquarters (meaning he wouldn’t want to attract the Ministry’s attention to it).
The Worst Spectator Events
I am not the only person to point out that the events of the Triwizard Tournament were poor replacements for having no Quidditch that year. While the first task was interesting to watch (not to say incredibly dangerous for everyone involved, including the spectators), the second task happens under water out of everyone’s sight, and the third happens faraway inside an opaque maze.
How Does Magic Work?
Barty Crouch Sr. is described as “powerfully magical” by Sirius. Why are some wizards better than others? The books never properly explain the basis for one wizard being better than another.
In The Deathly Hallows, Crabbe uses Fiendfyre to make a blaze that rivals Dumbledore’s fire conjuration ability at the lake in the Half Blood Prince. Crabbe is often described as a completely incompetent and rather stupid student, so it is inconsistent that he should be able to create such a powerful magical effect with almost no effort.
In general, the books equate academic achievement with magical ability, as in the cases of Dumbledore, Voldemort and Hermione, and they equate bad academic achievement with bad magical ability, as in the case of Neville.
Judging by the books, high intelligence is necessary to properly understand the theory behind the various spells, and a lot of training is needed to improve one’s skill at performing them (judging by the amount of training Harry needs with Hermione to master accio). The theory part of the spells is never described and the author ignores it completely in the case of Harry learning how to produce a patronus, for example. He only needs to learn an incantation to start doing the practical training. And when it comes to Harry training Dumbledore’s Army, he is never described as doing anything beyond overseeing practical training sessions. The books never properly explain where theory comes in.
The author seems to assume that magical ability comes from a combination of intelligence (IQ), theoretical and practical effort, and perhaps some secret magical sauce.
Dumbledore is a great wizard and you can probably never be as good as him no matter how hard you try.
The Imperius Curse
After Voldemort’s rebirth, he uses the Imperius Curse on Harry to make him bow down to him. Rowling says this is the third time in his life that Harry experiences the feelings associated with being Imperiused. Yet she mentions earlier in the book that Moody used the curse on Harry four times in a row during one class until he could fully throw the curse off. We also know that Moody put the curse on Harry during his first ever Defense Against the Dark Arts class with Moody, which means that when Voldemort used the curse on Harry, it was at the least the sixth time he was experiencing it.
Owl Post Speed
After the first task (November 24, 1994), Harry writes Sirius a long account of how he completed the task. Harry sends his letter using Ron’s owl Pigwidgeon, and receives Sirius’s reply close to the Yule Ball, some time between the 18th and 24th of December.
Even though Sirius is in England, Pigwidgeon’s round-trip takes almost an entire month. We know Sirius is in England because two days before the first task, Sirius breaks into a wizarding home and uses their fireplace to communicate with Harry using the Floo Network, a network that is specific to Britain, as it is under the control of the British Ministry of Magic.
In The Chamber of Secrets, the Ministry takes perhaps 40 minutes to send Harry a warning when Dobby uses a hover charm in the Dursley home. Privet Drive, where Harry lived, was somewhere in Surrey, about 25 miles from central London. This is close to real-life owl flying speeds (40 miles per hour), giving a few minutes to Mafalda Hopkirk to write and send out her warning letter.
As the entire length of the island of Britain is 600 miles (from the tip of Scotland to Plymouth), any uninterrupted owl trip from somewhere in England to another place should take no more than 10 hours. Assuming owls need rest and time to hunt on such a long trip, we can give an extra 5 hours, making the trip last 15 hours, though it is anyone’s guess how an owl with a large letter tied to its legs can hunt.
Therefore Sirius should have received Harry’s letter in less than a day, and he should have been able to send back his reply just as fast.
The Wand Order Mistake
When Voldemort’s wand is regurgitating his last few murders, James Potter comes out of the wand before Lily, even though James was killed first, and the murders are supposed to be played in reverse (most recent first). This error is fixed in later editions.
Harry’s Eye Malfunction
At the ending of The Goblet of Fire, Harry is described as keeping a watch for the arrival of the horseless carriages to take them to Hogsmeade Station. Ron asks for Krum’s autograph, and Hermione turns away, “smiling at the horseless carriages” that were coming toward them.
Since Harry has seen Cedric die, he should have been able to see the thestrals that were drawing the carriages. Instead, his moment of wonder at seeing the thestrals is saved for the The Order of the Phoenix.
This inconsistency appears to have been caused by the fact that the author had yet to invent thestrals when she was writing The Goblet of Fire.
How Did Harry Get His Map Back?
The fake professor Moody takes Harry’s Marauder’s Map and keeps it to the very end, when he is found out and eventually kissed by a dementor. The author forgets to include a scenario in which Harry gets the map back. He just happens to have it in his possession in the The Order of the Phoenix.
The Unimaginative Potter
At the beginning of the book, Harry is so desperate to listen to the Muggle news that he has to lie down on his back in his uncle’s flower bed to hear the news coming out of the window. If he had spent just ten minutes thinking of a more sensible way of listening to the news, he could have written Hermione to send him a portable radio and a headset. He was in touch with her, and she was in touch with her parents via owl post (in the same book, she borrows Harry’s owl to let her parents know she has become a prefect). Harry couldn’t have been so clueless about Muggle technology to not have known about radios and headsets (the headset to keep his uncle’s family in the dark regarding his news listening habit).
He could have also just used his invisibility cloak, as a reddit poster suggested. [Added on Oct 6, 2017]
Hedwig Overcomes the Fidelius Charm
Harry is able to send letters to Grimmauld Place even though it is under a Fidelius Charm, meaning none other than those given the secret should be able to see the place or interact with it. For example, Harry is unable to see the place until he is given a note by Dumbledore that tells him the secret. But before Harry is given the secret, Hedwig is able to get into the place to deliver letters, and once Harry does get a chance to visit the house, he finds that Hedwig is already there in the bedroom where he and Ron later sleep.
In Chapter 5 (“The Order of the Phoenix”), Sirius says that his “big disguise” (the fact that he can turn into a dog) is useless since Wormtail is bound to have told Voledemort about it by now. The implication is that after the events at the end of The Prisoner of Azkaban when Wormtail goes back to Voldemort, Wormtail would have had a chance to tell Voldemort about Sirius being an animagus.
In The Prisoner of Azkaban, Sirius says that Wormtail had been passing information about the Potters for a year before their death, so he would have had a year to tell Voldemort that Sirius was an animagus. Therefore there is no reason to assume that Wormtail’s going back to Voldemort now should have had any effect on Sirius’s disguise, as Voldemort almost certainly already knew, a decade and a half ago, that Sirius was an animagus.
The Missing Prefects
When Ron receives his letter announcing that he has become a prefect, Rowling mentions that Harry had forgotten that prefects would be chosen in their fifth year. If prefects are chosen every fifth year, there should have already been a pair of sixth year prefects, and a pair of seventh year prefects. Thus every house should have six prefects at any given year. It is strange that the only Gryffindor prefect ever mentioned during Harry’s time at Hogwarts is Percy, even though Harry should have met at least seven pairs of Gryffindor prefects besides Ron and Hermione by his sixth year (three pairs in his first year, and a new pair every year after that).
Dennis Creevey (Colin’s younger brother, who enters Hogwarts in Harry’s fourth year and falls into the lake) is mentioned as attending the founding meeting of the DA at the Hog’s Head, even though he is only a second-year, and second-years are not allowed to visit Hogsmeade. It is possible that he somehow sneaked out, though if the author had meant this to be the case, she probably would have made a reference to it.
How Did Dumbledore Justify Arthur Being at the Department of Mysteries at Midnight With an Invisibility Cloak?
After Arthur is attacked by Voldemort’s snake, Dumbledore somehow magically convinces the Ministry that Arthur wasn’t doing anything wrong. This is the same Ministry that hates Dumbledore and would love finding new reasons to persecute him and his supporters.
Perhaps Rowling had so much difficulty answering this question that she decided to solve the problem by ignoring it.
Harry Doesn’t Know What Year It is
When Kreacher disappears around Christmas, Harry expresses the fear that he might have left the house. Sirius says that house elves cannot leave the house, but Harry mentions that “two years ago” Dobby had done just that, leaving the Malfoy house against orders to come and warn Harry about the Malfoy plot.
“Two years ago”, counting from Book 5, would refer to Christmas of the the third year, on which Harry receives the Firebolt sent to him be Sirius, which is almost a year and a half after Dobby came to warn Harry (on Harry’s birthday) at the beginning of Book 2.
Harry is just a human, so there is nothing surprising about someone miscalculating time during a casual conversation. But since this a book with an author, either the author placed the error in here intentionally, or she didn’t bother to think too hard about the time differential between the two books. I lean toward the latter explanation.
Snape and the The Dark Lord
During one of their Occlumency lessons, Harry taunts Snape by telling him that he has only heard Death Eaters call Voldemort the “Dark Lord” (which Snape keeps doing). He is wrong about this, as Olivander refers to him as such in Harry’s first year, Dobby and Ginny call him the Dark Lord in Harry’s second year (she in her Valentine’s poem to Harry), and in Harry’s third year, he hears Trelawney calls him that. In his fourth year, Barty Crouch, Sr. calls him that too in his madness when he comes to Hogwarts to warn Dumbledore regarding Voldemort’s return.
Of course, it makes complete sense that Harry would ignore these facts, or not have them in mind at that particular time, since he is only venting his anger at Snape.
Hermione launches a crusade to defend elf rights, yet she calls the new centaur teacher a “horse”, which is similar to calling a human an ape, a degrading word that reduces its target to an animal. This is very out of character for her. She is intelligent and empathic enough to know that elves deserve the same treatment as humans, yet for some unknown reason she acts against her own nature to call a centaur a horse, for no good reason other than proving to a classmate that she is not losing out by not attending the centaur’s lessons.
Their Third Year
When Harry and Cho go to Hogsmeade on Valentine’s Day, Cho asks Harry if he remembers their playing against each other “in the third year”. That year was only Harry’s third year, it was Cho’s fourth, since she is a year older than Harry. Therefore she should have said “in your third year”, or at any rate she should have used another method of referencing that particular period of time.
Dumbledore’s Sort-of Broken Promise
When Dumbledore is about to make his escape, he tells professor McGonagall that he is not run leaving to go into hiding, that Fudge will soon wish he’d never dislodged him from Hogwarts, and then he says “I promise you”. But Dumbledore does go into hiding for about two months, from mid-April to mid-to-late June. Dumbledore’s words suggest that he wouldn’t be away for any perceivable length of time, but two months is a very long time in which a lot can happen.
The Junior Assistant That Wasn’t There
After the delicious events in which Umbridge finds out about Dumbledore’s Army and takes Harry to the headmaster’s office, J.K. Rowling says that it became public knowledge that Dumbledore had overcome two Aurors, Umbridge, Fudge, and his Junior Assistant to escape. But right before Dumbledore’s firey escape, Fudge sends Percy off to send an owl. Percy runs off, slamming the door behind him. There is no mention of him coming back. This means that when Dumbledore overcomes his adversaries in the office, the Junior Assistant is not in the room, so Dumbledore does not overcome him.
The Hagrid Who Became McGonagall
After Harry watches his father bully Snape in the Pensieve, Rowling mentions that McGonagall had described James and Sirius as forerunners of the Weasley twins. But in fact, it is Hagrid who says that the Weasley twins could give ‘em a run fer their money, McGonagall makes no such remark anywhere in the books.
The Overly Long Events at the Ministry
This is somewhat nit-picky, but it is still a valid point, so I decided to include it. Dusk falls as Harry and his friends ride the thestrals toward the Ministry. When they reach London, darkness has fully descended. It is the end of June. The evening twilight ends around 10:00 PM in London at this time of the year, so full darkness falls after 10:00 PM. Let’s assume Harry and his friends arrived at 11:00 PM. When all the events at the Ministry are over, Harry takes a Portkey back to Hogwarts in Scotland. It is mentioned once Harry is there, the sky is getting light. In Scotland around this time of the year, the morning twilight starts around 3:30 AM, and it gets visibly light somewhere between 3:30 AM and 4:00 AM. Let’s assume Harry arrives at 3:45 AM. This means that the time that elapses from Harry getting to the Ministry to his getting back to Hogwarts is 4 hours and 45 minutes.
But the events described in the books shouldn’t have taken more than two hours. Harry and his friends get to the Ministry, they rush to the Department of Mysteries, they meander around the various attractions the department offers until they find the Hall of Prophecy, at which point they meet the Death Eaters. A fight ensues, ending with the Order arriving and a very short showdown between Dumbledore and Voldemort, after which Harry is sent back to Hogwarts.
Harry should have gotten back to Hogwarts around 1:00 AM, hours before it got light.
Where Was the Order?
Throughout the book, members of the Order of the Phoenix are often mentioned as being on guard duty at the Ministry of Magic, to protect the prophecy from Voldemort. Why was no one from the Order on guard on the evening that the Death Eaters take over the Ministry?
Why Did Voldemort Not Go After Trelawney?
Voldemort spends an entire year (from the end of Book 4 when he returns to the end of Book 5) plotting to get his hands on the prophecy. In Book 6, Dumbledore mentions that Trelawney would have been in great danger from Voldemort had he not hired her to allow her to enjoy the protection offered by Hogwarts Castle. The question arises, once the glass orb that held the prophecy breaks in The Order of the Phoenix, why did Voldemort not switch to hunting down the next best available source, Trelawney?
Even if Voldemort had good reasons for not going after Trelawney, or at least making a small bit of effort, the author should have gone to the trouble of explaining his thinking. Just a month or so after the loss of the prophecy, Voldemort charges Draco Malfoy with the job of killing Dumbledore. Couldn’t he have also given him the side job of using one or more unforgivable curses on Trelawney until she gave up her secret?
Even more importantly, Voldemort has Hogwarts under his control for almost an entire year starting with about a month after Dumbledore’s death when the Ministry falls, and during this time Trelawney presumably stayed at Hogwarts, as she is present with the rest of the Hogwarts teachers at the Battle of Hogwarts. Why did Voldemort not make any effort to get the prophecy out of her?
We know that Trelawney doesn’t remember her own trances, so it is unlikely that she would have remembered the prophecy. But Voldemort didn’t know that (which is why Trelawney was in danger of Voldemort to begin with), so her potential inability to help him out does not explain his complete lack of interest in going after her.
The Trace is probably the single worst idea in the entire series, so bad that even the author doesn’t take it seriously. In The Chamber of Secrets, the Trace causes the Ministry to blame Harry for magic done by Dobby. As explained by Dumbledore in The Half-Blood Prince, the Trace is location-based, so that if magic is done at a muggle home, the magic is immediately blamed on any residing wizard, while magic done at a wizarding home is ignored, even if done by children, since the Ministry assumes it is the parents that are performing the magic.
In The Goblet of Fire, when Mr. Weasley and his sons come to pick up Harry, Mr. Weasley performs ample magic, including a powerful spell to destroy the wall/boards that blocked the fireplace. Why doesn’t the Ministry blame Harry for this magic? It can be said that Mr. Weasley alerted the Ministry to his visit, but no mention of this is made.
In The Order of the Phoenix, a large number of wizards arrive at the Dursley home to pick up Harry, again doing a lot of magic while there, and again, the Ministry doesn’t pick up on it. Lupin mentions that they cannot use the Floo Network to take Harry out of his aunt and uncle’s house because the Ministry would be watching it, which means that it is quite unlikely that they alerted the Ministry to their presence at the house.
In The Half-Blood Prince, Dumbledore does a lot of magic in the Dursley home (making glasses fly, moving the sofa), again without the Ministry blaming Harry for it.
In The Deathly Hallows, in another twist, when Harry is staying at the Burrow a few days before his birthday, Ron says that Harry cannot do anything about the Horcruxes yet since he still has the Trace on him, speaking as if the Trace is wizard-based, rather than location-based as Dumbledore had said. Of course, it would have been a bad idea if Harry had used magic before he came of age, even after leaving his aunt and uncle’s, since it would have given the Ministry justification for arresting him if he were witnessed doing magic. But there is no reason to mention the Trace in such a context, since by leaving his aunt and uncle’s, Harry has left the Trace behind for good.
Should I Hold on Tightly or Not Dumbledore?
In Chapter 4, when Dumbledore is about to take Harry to Budleigh Babberton where Slughorn lives using Side-Along-Apparition, he tells Harry, “you will need to hold on to my arm very tightly”. In Chapter 25, when the two are about to apparate to Voldemort’s cave, Dumbledore tells Harry, “There is no need to grip too hard, I am merely guiding you,” which sounds like it contradicts his earlier guidance. Of course, he could have meant that Harry should hold on tightly, just not too tightly. [Added June 28, 2017]
Why was Slughorn not curious about how Dumbledore had tracked him down?
Slughorn says he has been on the run for a year and out of touch with everyone. Yet Dumbledore is able to find him. The strange thing is that Slughorn displays no curiosity whatsoever about how Dumbledore had been able to discover his hiding location. For a person on the run, this should have been the first thing on his mind: “How was I discovered?” If even Voldemort cannot track him down, how could Dumbledore? Shouldn’t this suggest to him the existence of a potentially fatal weakness in his defenses that would enable skilled wizards like Dumbledore and Voldemort to track him down? [Added September 17, 2018]
The Walk from Hogsmeade Station
After Malfoy breaks Harry’s nose, Harry and Tonks walk to Hogwarts, as all the carriages have left. Rowling mentions that Harry had never appreciated how far Hogsmeade Station was from Hogwarts, since he had never had to walk, having always travelled by carriage. But it is seems unlikely that the distance would have been such a surprise since the students always went on their Hogsmeade visits on foot, and the name of the station suggests that it is probably somewhere close to the village.
Of course, it is possible that the station and the village’s names were both references to something that was not very close to either, and that the two were not very close either.
Dumbledore’s Lapses of Memory
In The Prisoner of Azkaban, Dumbledore proudly tells Snape that his memory is as good as it ever was when Snape asks him if he remembers what he had told him regarding the potential dangers of hiring Lupin. In The Half-Blood Prince, however, Dumbledore is guilty of two serious lapses of memory that makes me wonder if old age was not finally creeping up or him, or if the curse on Marvolo’s ring had somehow affected his brain.
Dumbledore mentions that No. 12 Grimmauld Place was made Unplottable by the Order of the Phoenix. However, in the The Order of the Phoenix, Sirius mentions that it was his father who put various protections in place at the home, including making it Unplottable (saying Muggles couldn’t come and call). As Sirius had spent many years of his life in that house prior to it being headquarters for the Order, it is unlikely that he would have misremembered an important fact like that. Therefore the most straightforward conclusion is that Dumbledore was wrong about the Order making the house Unplottable.
The second lapse of memory is Dumbledore saying, in chapter 23, that Voldemort used Nagini to kill an old Muggle man (Frank Bryce) in the summer when the Quidditch World Cup final was held (as is described at the beginning of The Goblet of Fire). The truth is that it was Voldemort who killed Frank, with the Killing Curse. Harry does not correct Dumbledore, perhaps suffering from a sudden onset of unusually selective amnesia.
Harry’s Lapse of Memory
Speaking of lapses of memory, in chapter 10 (“The House of Gaunt”) Harry and Dumbledore take a trip to Little Hangleton in the Pensieve. This is the same place that Harry spends at least an hour, perhaps two, of one of the most memorable episodes of his life; his witnessing the return of Lord Voldemort. In both cases the visible presence of a large manor house (the Riddle House) is mentioned. How come there is no mention at all of Harry remembering Little Hangleton from his previous trip to the village?
The Magical Chair
Rowling describes the child Voldemort’s room as containing nothing besides an old wardrobe and an iron bedstead. Yet she mentions Dumbledore drawing up a chair to sit closer to Tom. This could be a brilliant joke on the reader and on Tom, as she is mentioning Dumbledore doing magic (conjuring a chair) that neither the readers nor Tom notice. It is also possible that she simply forgot that the room didn’t contain a chair, or forgot to mention the room containing one.
The Werewolf on Vacation
Lupin sleeps in Bill’s bedroom on Christmas Eve, staying at the Burrow for Christmas. It so happens that the night of Christmas Eve of that year (1996) was the night of a full moon, therefore he should have been nowhere near humans. Even if he had the use of the Wolfsbane Potion, he would have been in no state to enjoy any festivities and would have done better to stay home.
When Harry is spending the night at the hospital wing with Ron (after McLaggen cracks his skull with a Beater’s bat), he is able to summon Kreacher simply by calling his name when he wants to ask him to tail Malfoy for him.
In the previous book, Dumbledore says that house elves cannot disobey a direct order, using this to explain why Kreacher couldn’t have told Narcissa and Bellatrix secrets on the Order of the Phoenix, as Sirius had forbidden Kreacher from repeating said secrets to outsiders.
If Harry is able to summon Kreacher simply by calling him, and this being a direct order, why can’t Sirius call Kreacher in the same way in the The Order of the Phoenix when Kreacher is out of the house?
Either house elves can disobey direct orders, and thus Kreacher could have told Cissy and Bella the secrets of the Order, or they can’t, and thus Kreacher should have apparated right into No. 12 Grimmauld Place once Sirius called for him, the way he apparated into the hospital wing when Harry called for him.
The Too-Clever-By-Half Summoning Charm
When Harry is in the cave with Dumbledore, he is able to summon the fake horcrux in the middle of the lake using a Summoning Charm through the incantation “Accio Horcrux”. Since the locket in the middle of the lake wasn’t a horcux, the spell shouldn’t have worked, unless the spell was clever enough to know what Harry wanted, and to know that that particular object in the middle of the lake (as opposed to, say, the thousands of pebbles in the area) stood for whatever Harry had in mind. The books never mention the Summoning Charm as being anything other than a way to get something regardless of where it is (as in Harry using it to get his Firebold, even though he was so faraway from the castle that there is no way he could have known its exact coordinates). Harry’s Summoning Charm was for the real horcrux, not the fake one, therefore it should have been directed at the real horcrux (and then it should have failed due to the horcrux being too faraway).
Did the Summoning Charm have a fall-back mechanism so that if the real object wasn’t obtainable, the nearest equivalent would have been magically towed to the spell caster?
The simplest explanation is that the author didn’t consider too carefully the ramifications of a Summoning Charm acting upon an object other than what was really meant by the caster of the spell.
The Abandoned Cloak
After Snape kills Dumbledore, Harry is in such haste to get to the Death Eaters that he leaves his cloak on top of the Astronomy Tower. There is no mention of him going to get it back. It is mentioned that Ministry Wizards investigated the site of the murder (seeing that there were two broomsticks there, deducing that Dumbledore had a companion with him), therefore they should have been able to notice the cloak and get their hands on it, potentially confiscating it.
This is not exactly an error or inconsistency, but it is a little strange. On Harry’s birthday, right before Scrimgeour’s visit to the burrow, a conversation is mentioned between Charlie and Hagrid in which Hagrid asks about his pet dragon Norbert (which Harry and Hermione sent away with Charlie’s friends on the first year), and Charlie corrects him, saying that they now call her Norberta, since it is a female dragon. It is a little strange that it took Hagrid six years to find out that they now call his beloved dragon Norberta. The Goblet of Fire mentions at least one conversation between Hagrid and Charlie (when Hagrid takes Harry and Madame Maxime to view the dragons), why didn’t Hagrid ask Charlie about his dragon then? And why didn’t Hagrid send Charlie a letter throughout all those years to ask him how his dragon was doing?
Maybe Hagrid simply had too much on his mind, or maybe he didn’t have such a long attention span, so that once the dragon was taken away, he found other things on which to practice his love for monsters (as in Buckbeakf in The Prisoner of Azkaban).
Escape by Disapparition
Since the Ministry has made it a crime to disapparate within or near the Dursley home, Dedalus Diggle takes the Dursleys ten miles out and away from the home before disapparating them to a safehouse. The question is, why didn’t the Order use the same method to go to safety, rather than flying all the way to the safehouses? Mundungus is able to successfully escape by disapparating. The rest of the Order could have done the same (perhaps flying for a few miles out just to be safe), instead of giving the Death Eaters the chance to attack and kill them across England until they reached their safehouses.
Why Didn’t they Use 14 Potters?
Had they used 14 Potters for the escape, Voldemort and his Death Eaters would have been even more confused, and they would have been less likely to use extreme force against any of the members of the Order, as any of them could have been Potter.
Why Wasn’t Snape Asked to Check Grimmauld Place?
Once Harry and his friends flee from the wedding, the Death Eaters are mentioned as searching all over the country to find them, sending some of their numbers to Grimmauld Place to look for signs of their presence.
Hermione says that Voldermort would have sent Snape after them if he had known that they were in there. But instead of sending his servants to look at Grimmauld Place day after day from the outside, couldn’t he have just sent Snape to go inside and see if Harry was there? Snape couldn’t mention the name of the place, but he was perfectly capable of going in.
Why Didn’t Voldemort Turn the Sword of Gryffindor into a Horcrux?
Early in the book, Voldemort takes over the Ministry (and presumably Hogwart). In September it is announced that Snape has been made headmaster, by Voldemort’s appointment of course. Once Voldemort had posession of Hogwarts, he also had posession of the Sword of Gryffindor. Voldemort knows that one of his horcruxes is destroyed (the diary that was destroyed by Harry), so he is one horcrux short of the seven horcruxes he so ardently desired. And now that he had posession of another one of the relics of the Hogwarts founders, why didn’t turn it into a horcrux like he did the other three relics?
Couldn’t Snape Apparate Some Death Eaters into the House?
As Yaxley is able to hold onto Hermione and force himself to get inside No. 12, Grimmauld Place, couldn’t a Death Eater have done the same with Snape? We know that both Hermione and Snape were under Mad-Eye’s tongue-tying curse (as they had both visited the place after the curse was in place), therefore the tongue-tying curse wouldn’t have affected Snape’s ability to bring some of his Death Eater pals over to the house the same it didn’t affect Hermione’s ability to bring Yaxley into the house.
The Cloak, Teleported
Before entering Xenophilius Lovegood’s house, Harry gives his cloak to Hermione, who puts it in her tiny beaded bag. Later, when they are about to apparate away from the house to escape the Death Eaters, Hermione asks Harry to give her the cloak, even though it should have been in her bag.
The Soaked Harry
Once the three friends disembark from the dragon, they are soaked due to having jumped into a lake and are suffering from burns all over their bodies from the protective charm that was on the Lestranges’ vault. They all change, then Hermione gives everyone dry robes and pumpkin juice. They change, then gulp down the juice. And then, Harry drips dittany through a singed hole in his jeans onto the angry burn beneath, even though he should have had a change of clothing, presumably not choosing to keep on his soaked wet and tattered jeans under the dry robes that Hermione handed him.
Later Harry reads Voldemort’s mind, then comes back to the here and now, realizing that he is still soaked, even though, as already mentioned, he should have dry robes.
Dumbledore and the Room of Requirement
This is mostly a nit-pick. In The Deathly Hallows, Rowling says that “those two model students” (professors Flitwick and Dumbledore) had never set foot in the Room of Requirement, since they had never had a need for such a room. But in the The Goblet of Fire, Dumbledore mentions using a room that sounds very much like the Room of Requirement during the Yule Ball, and in the next book, Harry convinces Hermione that the Room of Requirement is safe to use since Dumbledore had mentioned it.
It seems like Rowling had forgotten Dumbledore’s possible relationship to the room when she wrote the above in The Deathly Hallows.
The Words on the Diadem
The book mentions that the statement “WIT BEYOND MEASURE IS MAN’S GREATEST TREASURE” was etched on Ravenclaw’s diadem. The diadem is about 1000 years old. Modern English is so different from Old English that a modern English speaker can only be expected to understand English that goes back only 500 years. Anything older than that is way too different from the English we know, and a lot more similar to Dutch. Which means that the fact of that statement being on the diadem in perfect 18th century English is quite anachronistic, and very much an elementary error.
Snape in the Headmaster’s Office
When Harry is viewing Snape’s memories, he sees Snape being told by Dumbledore’s portrait in the headmaster’s office to bewitch Mundungus to make him suggest the Seven Potters scheme. This is just after Dumbledore’s death, and before the fall of the Ministry. Snape is a fugitive from the law, how could he stroll into Hogwarts and hold a cosy conversation with Dumbledore when he was wanted for murder?
Multiple explanations can be mentioned, but the most likely one is that the author was thinking that Snape was the headmaster when she was writing this part of the book, forgetting that he becomes headmaster months later and after the fall of the Ministry.
Why Did Voldemort Not Use the Killing Curse on Snape?
We know that the Killing Curse is a big favorite with Voldemort, but when Voldemort attempts to become the master of the Elderwand, he uses Nagini to kill Snape, rather than the Killing Curse. This is a tremendous risk, since how can he be sure that the wand will recognize the snake’s owner as the killer?
The reason that Voldemort uses the snake rather than the logical choice is that Rowling needed to give Snape time to give his memories to Harry. The Killing Curse wouldn’t have allowed this.
In the Pensieve, Lily says that Snape implying Lupin is a werewolf is a “theory”, yet she says she knows James saved him in the tunnel, saved him from what if not from a werewolf?
The Miracle That Wasn’t
In the Pensieve, there is a scene inside the headmaster’s office where Snape says it’s a miracle Dumbledore managed to return to Hogwarts after putting on the Marvolo ring that carried a curse. Dumbledore admits that he thought breaking open the ring with the Sword of Gryffindor would also break the curse.
But earlier in the book Phineas Nigellus says he watched Dumbledore break the ring open in the headmaster’s office, and since we know he put the ring on after he broke it open, he would have been already in the headmaster’s office when he put on the ring. So there was no miracle in him returning to Hogwarts; he was already at Hogwarts when he put the ring on.
Harry’s Biggest Mistake
At the end of the book, Harry refuses to carry the Elder Wand, instead deciding to put it back with Dumbledore’s remains, so that when he dies, the power of the wand breaks.
If his goal is to break the power of the wand, wouldn’t it have made a lot more sense to just break the wand as he does in the film?
By the end of the book, it becomes public knowledge that Harry is the rightful possessor of the Elder Wand during Harry and Voldemort’s last debate in the Great Hall, where they had an audience of hundreds. What this means is that any dark wizard who wishes to become really powerful has a strong incentive to hunt down Harry and kill him in order to become the rightful owner of the Elder Wand.
Harry did not avoid trouble by refusing to carry the wand. He simply refused himself its benefits while putting himself fully at the mercy of any dark wizard that seeks the wand’s power.
Lupin and Hagrid go on missions for the Order, to convince their own kind to support Dumbledore’s cause. The books never mention any fruit that may have come from their efforts. Hagrid happens to bring his little brother back, who helps in the Battle of Hogwarts. It would have been nice if some fruit of Lupin’s efforts had been mentioned, for example a Werewolf pal of his helping out Harry and his friends at some point.