Before the first Quidditch match, Harry is relieved that it's cloudy as he won't have the sun in his eyes, but moments later the stadium is in "dazzling sunlight".

Second-year student Dennis Creevey goes to the Hog's Head for the first DA "meeting", but only third-years and older are allowed to go to Hogsmeade during term time. For those of you who don't believe us and insist that he's a third-year, open your copy of Goblet of Fire to see him introduced in the chapter involving the Sorting Ceremony (making him a second-year in Order of the Phoenix). Don't e-mail us saying that this is a mistake of ours -- it isn't.

Harry gets off the train and is able to see the Thestrals. It is later explained that you can see them after you have seen death. Harry had seen the death of his mother and possibly his father before he saw Cedric Diggory die, so why didn't he see the Thestrals before?
JKR's response: You can't see them until the death "sinks in."

Chapter 28, pages 625-626, Malfoy starts docking points from both Gryffindor and Hufflepuff after becoming part of the Inquisitorial Squad and Ernie Macmillan says, "He can't be allowed to dock points...that would be ridiculous...It would completely undermine the prefect system..." But in the second book, chapter 9, page 158, Percy, a prefect at the time, takes 5 points from Gryffindor after finding Ron, Hermione, and Harry looking around Moaning Myrtle's bathroom. So how was Percy able to take points from Gryffindor if prefects aren't even able to?
Possible Explanation: The prefects may be allowed to dock points from their houses, but not from other houses. - Thanks to everyone who wrote in!

There's an illustration mistake in chapter thirty-eight, The Second War Begins. Nymphadora Tonk's t-shirt is supposed to say 'The Weird Sisters'. In the illustration, you can't see all of the writing, but if you look closely you can see that only an 'erd' is visible on the first line. Since 'weird' has an 'i' after the 'e', the 'i' should be visible as well--but it's not.

Page 120: "'He came last night, while you were in bed,' said Mr. Weasley. Harry dropped his own eyes to his plate. The thought that Dumbledore had been in the house on the eve of his hearing and not asked to see him made him feel, if that were possible, even worse."
But the hearing is the following morning from that. So Dumbledore wasn't there on the eve of the hearing, but two nights before!
Possible explanation: It's possible that Dumbledore came after midnight, which would be considered the eve of the hearing, but is still sometimes referred to as "last night" by people. This is more than likely because the book also says that Harry was not sleeping well, and maybe he could not fall asleep until past midnight.

In book 1, Hagrid said that Lily and James where Head Boy and Girl. However, in book five, it's said that James was never a prefect.
JKR's response: You don't have to be a prefect to be a Head Boy or Girl.

On page 710 it says that Parvati and Lavender were practicing basic locomotion charms making their pencil cases race each other. They use scrolls and quills, what would they be doing with pencil cases?

Arguable: Page 147: "'Dumbledore was having real trouble finding a new Defense Against the Dark Arts teacher this year. Not suprising, is it, when you look at what's happened to the last four?' said George. 'One sacked, one dead, one's memory removed and one locked in a trunk for nine months.' Quirrel is dead, Lockhart's memory's gone, Moody was locked in the trunk but Lupin didn't get sacked, he resigned".

When Harry is talking to Professor McGonagall about career advice and Aurors, McGonagall says: "I don't think anybody has been taken on the last three years." But, at the begining of the book, Tonks says, (about her becoming an Auror) "I only qualified a year ago."
Possible explanation: McGonagall meant that no one had been accepted in the advanced Auror training program, not as an Auror, in the past three years. She had mentioned that for Harry to be an Auror he had to first attend another more advanced training that takes 3 years. That means that Tonks was accepted into the training for Aurors 4 years ago. She was a fully qualified (for one year) Auror when she met Harry.

In chapter 28, page 626, Malfoy docks Ron five points because his shirt's untucked, but since they were in between classes, Ron would being wearing his robes, not a shirt.
Possible explanation: Malfoy was referring to the shirt that Ron wears underneath his robes.

On page 166, chapter 9 ("The Woes of Mrs. Weasley"), it says: He pretended to be rummaging for something while Hermione crossed to the wardrobe and called Hedwig down. A few moments passed; Harry heard the door close but remained bent double, listening...He straightened up and looked behind him. Hermione and Hedwig had gone. Harry hurried across the room, closed the door...Yet, Harry had already heard the door close.

On page 504 of the American OotP, Harry says, "Dobby did, he left the Malfoys' to give me warnings two years ago. He had to punish himself afterward, but he still managed it." This is in the fifth book, and what he is talking about happened in the second book. So, it wouldn't be two years ago, but in fact three years ago.

In book 3 when Neville lost all the passwords and Sirius gained entrance into the Gryffindor tower, Neville is banned from all of the Hogsmeade visits. But, on page 339 of book 5 he is in the Hog's Head with the DA.
Possible explanation: Maybe Neville was only banned from all Hogsmeade visits during that year, and not for the rest of his career at Hogwarts. Another explanation may be that when it was found out by Dumbledore that Sirius Black was innocent, the ban on Neville was lifted.

We are told that fifth-years are allowed out in the corridors until nine o'clock. Later in the book, during the DA meeting when Umbridge comes hunting for the group, Harry hopes that his fellow DA members will have the sense to take refuge in the library, the Owlery, or a bathroom instead of trying to make it all the way to their dormitories, because it is only ten to nine. However, not all the members of the DA are in fifth-year or above, so they would not be allowed in the corridors at ten to nine, and they would have to make it all the way to their dormitories or else get in trouble anyway.

In book 5 on page 185, the Sorting Hat sings:
For instance, Slytherin
Took only pure-blood wizards,
of greay cunning, just like him.
However, Voldemort wasn't a pure-blood and he got sorted into Slytherin.
Response from Lisa: The key word in the above phrase is "took". It doesn't mean that the house only allows pure-bloods anymore, it means that it USED to only allow pure-bloods. Also, Tom was the heir of Slytherin. So there is no doubt he would be in that house, even if he was a half-blood.

In book 5, page 117, 6th paragraph, it states, "Snape might refer their work as 'cleaning' but in Harry's opinion they were waging war on the house...." Shouldn't it be Sirius? After all, it was his house they were cleaning.
Repsonse from PotterFan651: On page 83 (American), Sirius says, "...listening to Snape's reports, having to take all his snide hints that he's out there risking his life while I'm sat on my backside here having a nice comfortable time...asking me how the cleaning's going..." So, Snape did refer to their work as cleaning.

In the British version of book 5 on page 480, when naming the death eaters who escaped, it says, "Algernon Rookwood, convicted of leaking ministry of magic secrets to he who must not be named." and in the British version of book 4 on page 512 it states: "Rookwood? said Crouch, nodding to a witch sitting in front of him, who began scribbling upon her piece of parchment. Augustus Rookwood of the Department of Mysteries?"

The Order of the Phoenix, chapter twenty-seven, page 614:
"Oho!" said Fudge bouncing up and down on the balls of his feet again. "Yes, do let's hear the latest cock-and-bull story designed to pull Potter out of trouble! Go on, then, Dumbledore, go on ---- Willy Widdershins was lying, was he? Or was it Potter’s identical twin in the Hog’s Head that day? Or is there the usual simple explanation involving a reversal of time, a dead man coming back to life, and a couple of invisible dementors?" Fudge never knew about Hermione and Harry using the Time Turner to go back in time to save Sirius and Buckbeak.

Questionable (JKR said that the death has to "sink in" in order to see the thestrals): On page 628 to pg 629 Harry, Ron and Hermine are waiting for the carriages to take them back to the Hogwarts Express and they mention the horseless carriages twice "...the carriages would take them back to the Hogsmeade station" and "...smiling at the horesless carriages.." But as it states, the three clearly saw the carriages but Harry doesn't mention the Thestrals. He should see them since earlier in the book he had seen Cedric die.

Page 714: It says that when they are taking they O.W.L.s practical exam that Harry is performing for his judge and he says that Hannah Abott was trying to vanish a iguana! But they wre called in in alphabatical order by last name, so why would Abott and Potter be together?

O.W.L.s are taken in fifth year and N.E.W.T.s are taken in the seventh year. On page 228 Ron is talking to Harry and Hermione about what Bill had told him about the career advice meeting they'd be having that year. Ron says, "...so you can choose what N.E.W.T.s you want to do next year..." Next year they'll all be in the sixth year not the seventh, so they wont be taking their N.E.W.T.s next year.
Fan response: Harry, Hermione & Ron are able to choose what N.E.W.T. subjects they want to do next year, not necessarily that they are doing the exams. They prepare for their N.E.W.T. testing 7th year by taking the courses 6th year and 7th year.

When Harry is taken to Dumbledore’s office by Dolores and Dumbledore escapes, it says that next day that talk was going around about how Dumbledore had overcome two Aurors, The Minister of Magic, The High inquisitor, and Fudges junior assistant. However, Percy had left minutes earlier to send his notes to the Daily Prophet.
Possible Explanation: This was just a rumor, and rumors are often changed to make things seem more impressive.

In book five, chapter 30 (Grawp), pages 683 and 684, at the Gryffindor/Ravenclaw Qidditch match, it says: "They [Harry & Hermione] found seats in the topmost row of the stands." Later on, when Hagrid comes to take them to see Grawp, it says: "Apparently he [Hagrid] had squeezed his way all along the row behind." How can that be if Harry and Hermione were in the top row?

The cover of OotP shows Harry in the Department of Mysteries holding his wand in his left hand. However, it is clearly stated that his right arm is his wand arm.

In the Astronomy O.W.L. exam, Harry is completing his drawing of the constellation of Orion. At England's latitude Orion would only be visible approximately from November until March. However, they are taking their exams in June. - Thanks to Stuart and Sailor Unicorn

In book 3, Fred and George receieve their O.W.L. results before the end of school. However, in OotP, Harry, Ron, and Hermione have to wait until July to get their results. - Thanks to everyone who sent this in!

In the chapter "The Sorting Hat" in the first book (page 121), a "Perks, Salley-Anne" is sorted before Harry; however, in the fifth book (page 713) she is not called to take her O.W.L.S. - Thanks to Nathan
Possible Explanation: Salley-Anne Perks may have left the school between books 1 and 5.

On chapter 5, page 86, third paragraph, it reads: "... and then," choked Mundungus, tears running down his face, "and then if you'll believe it 'e says to me, 'e says, ''ere, Dung, where didja get all those toads from 'cos some son of a Bludger's gone and nicked all mine!' And i says, 'Nicked all your toads, Will, what next? So you'll be wanting some more, then?' And if you'll believe me lads, the gormless gargoyle buys all 'is own toads orf me for twice what 'e paid in the first place--" But two paragraphs down, he says "But, you know Molly, Will nicked 'em orf Warty Harris in the first place, so i wasn't really doing nothing wrong--" But how could Will buy all his own toads of Dung for twice what he paid in the first place if he stole the toads? He wouldn't have paid anything!

In Chapter 1, Harry hears a sharp crack, the sound of someone Apparating. Later in the book, when he arrives at Grimmauld Place, Fred and George are also Apparating in and out with sharp cracks. However, in previous books the sound of someone Apparating was a *pop*.

On page 625 (UK edition), 1st paragraph, it says: "You will sit the theory papers in the mornings and the practice in the afternoons." The word practice should be practical. -

On page 709 (UK edition), 4th paragraph, it says: "Harry flung the prophecy across the floor, Neville span himself around on his back and scooped the ball to his chest. Malfoy pointed the wand instead at Neville, but Harry jabbed his own wand back over his shoulder and yelled, 'Impedimenta!'" It should read "Neville spun himself" instead of "Neville span himself."

In Chapter 27 of book 5 ("The Centaur and the Sneak"), Professor McGonagall says that "usually when a person shakes their head, they mean 'no'. So unless Miss Edgecombe is using a form of sign language as yet unknown to humans..." Actually, in some countries and cultures, like in Bulgaria, you shake your head when you mean "yes" and nod when you mean "no."

Page 583, "Seen and Unforseen": After Harry had given his interview in the Quibbler about the night Voldemort returned, a disgruntled Umbridge banned the artical after its release, though this didn't keep students from finding out and reading it, including Seamus. Umbridge was monitoring the mail, both in and out of Hogwarts, as she said elsewhere in the book. Seamus, however, informed Harry that he beleived him and he'd sent the article to his mother. Obviously, there's a glitch here because Seamus surely would have been punished for being in possession of the article, had Umbridge come across it in the outgoing mail.

In OotP, page 60, it is describing Number Twelve, Grimmauld place. It reads:"The silver door knocker was in the form of a twisted serpent. There was no keyhole or letterbox." However, it clearly shows on the title page (the drawing of Snuffles exiting Number Twelve) that there a keyhole, and no letter box.

Educational Decree 24 bans all clubs, defining a club as "a regular meeting of three or more students," so shouldn't Harry, Ron, and Hermione get in trouble just for studying together every night?

On page 530 at Harry's first Occlumency lesson, Snape says "Only Muggles talk of 'mind reading.'" But on page 382 Ron states, "Harry, you're reading You-Know-Who's mind..."

There is no mention of Educational Decree number 25. 24 bans all clubs, 26 bans teachers from talking about the Azkaban breakout, 27 bans "The Quibbler," and 28 makes Umbridge Headmistress of Hogwarts. Why would J.K. Rowling leave out one of the Educational Decrees?

Chapter 21, page 454, American edition: At the last DA meeting prior to Christmas, the DA members are reviewing the stunning spell and the book states, "Space was really too confined to allow them all to work this spell at once: half the group observed the others for a while, then they swapped over." Since the Room of Requirement gives you exactly what you need, wouldn't it give them the necessary space as well? -

In chapter 28, "Snape's Worst Memory," Harry sees his father in the Great Hall, taking his Defense Against the Dark Arts O.W.L. It says that James "turned in his seat and grinned at a boy (Sirius) sitting four seats behind him." But in an exam they would be sitting in alphabetical order, so why is "Black" four seats behind "Potter"?