Other mistake: Dutch DVD Only: After their crashlanding at Hogwarts, Harry and Ron are taken to Snape who tells them the Willow has been standing there "since before they were born". The Dutch translation reads "over a thousand years". It's a minor mistake on itself, but in Book 3 we learn how long the Willow has really been standing there and that's nowhere near "over a thousand years".
Continuity mistake: Throughout the movie, when Ron and Harry are standing together their heights vary in wide shots and closeups.
Continuity mistake: At the end, when Lucius Malfoy is talking to Dumbledore, Malfoy has a couple strands of hair going down his cheek. Just after he says "Well, let us hope-" he turns his head and the hairs disappear.
Continuity mistake: At the Weasley kitchen table, Percy hands the Hogwarts letters to each of the twins. A few shots later, you see one of the twins again being handed the same letter, this time from a different angle.
Other mistake: When Tom said that he set Hagrid up Harry said that Hagrid is his friend. In Icelandic subtitles it is translated that Harry is his friend.
Continuity mistake: When Harry stabs the diary, it is completely soaked in ink, but when Professor Dumbeldore shows it to him it is partially dry. I doubt that Harry had time to escape the chamber, try and wash off the ink, and go to Dumbeldore's office. We see that stabbing the diary renders it powerless, so it can't have soaked up all the ink.
Continuity mistake: In the scenes where Harry & Ron are trying to get away from the spiders, the car windshield goes from not being broken to being broken constantly, from the time it comes over the hill to when it drops them off at school.
Other mistake: Dutch DVD Only: After the duel Harry tells he told the snake to keep away from Justin. In the subtitles, Justin's name appears untranslated. Later when Justin falls prey to the Basilisk he is called by name again but this time his name is translated to Dutch in the subtitles, namely "Joost".
Visible crew/equipment: In the Dueling Club scene, as Snape says "Don't move, Potter, I'll get rid of it for you" and walks towards the camera, a film crew chair can be seen on the left side of the screen.
Continuity mistake: When Harry drinks the Polyjuice potion you can see his hand, but in the next shot his robe sleeve is over his hand.
Continuity mistake: During breakfast at the Weasleys, when Mr. Weasley asks, "What is the function of a rubber duck?" Ron turns his head toward Harry waiting for his response, but in the next shot Ron is looking down at his food, before they all turn their heads to look out the window at Errol.
Plot hole: When Harry and Ron transform into Crabb and Goyle, he doesn't take off his glasses so then Malfoy can comment on them. Goyle doesn't need glasses - Harry's eyesight should've been immediately blurry, and he would have taken them off.
Suggested correction: For all we know Goyle does need glasses and either doesn't realise it or doesn't want to say it. When I was in high school for example, I used to give my glasses to students who couldn't read the board. They didn't wear glasses, but obviously should have had them if they could see better with mine. Plus it is shown from the film the potion Hermione made doesn't change things like internal voice boxes. It's reasonable to conclude it didn't work for eyesight either.
Continuity mistake: Tom Riddle's uniform tie is different to the current ties in the first two Harry Potter films. Yet it matches the style of the students ties in the rest of the films. The mistake here is that Tom Riddle (at school) was before Harry's time at Hogwarts, but I guess when the costume department changed the ties, they didn't realise they should give Tom Riddle an older one as per the first two films.
Continuity mistake: When Snape yells Expelliarmus and shoots it at Lockhart, he puts his left hand behind him. But, on the next overhead shot, his left hand is now stretched out to the side of him.
Continuity mistake: When Harry has Tom Riddle's diary and starts writing into it, he writes "My name is Harry Potter". You can see by the way he writes it he doesn't put a full stop (period) at the end of the sentence. But in the next shot of the diary, there suddenly is a full stop there.
Other mistake: When the spider busts the car window and attacks Ron, we hear chirping and wheezing as the beast tries to impale Ron with its fangs. Yet no fangs are visible, nor piercing into Ron, as he hollers at Harry to 'get going'. When he should have instead, been almost rendered unconscious.
Revealing mistake: The spiders advancing on Harry and Ron during the visit to Aragog are not the same in appearance. In some of the closeups a few have elongated bodies, while others are medium-sized. And many of them look quite aged, like Aragog himself.
Continuity mistake: Hermione tells Harry and Ron to grab the robes after they pass out, but the next scene she has Slytherin robes from the laundry.
Other mistake: Just before Hermione gives Harry and Ron the two drugged cakes for Crabbe and Goyle in the food hall, snow is falling and to a fairly low level. In spite of this, and it being a continuous shot, as the camera lowers down, the snow ceases, but right at the end of the shot, the camera view raises up a significant amount where we should be able to see the falling snow again, but someone wanted to save pennies on the VFX budget, because the snow has gone.
Other mistake: When Hermione is running around the Quidditch field to blow up the bludger, she makes it around the massive Quidditch field in seven seconds flat.
