Corrected entry: After Professor Lupin confiscated the Marauder's Map from Harry Potter, Harry told Lupin that he saw Peter Pettigrew's name on the map. Although both Lupin and Potter did have their own knowledge about Pettigrew, Lupin was his friend and Potter learned from overhearing the conversation between Professor McGonagall, Madame Rosmerta and Cornelius Fudge, there was no indication that they ever had any conversation about Peter Pettigrew. Lupin's reaction to Harry's revelation was rather odd because he looked worried instead of surprised that Potter already had some information about Pettigrew. Potter himself also seemed really familiar with the name rather than showing any indication of curiosity about Pettigrew. Such a profound discovery should have made him question Lupin about the nature of the finding rather than just walking away from his office. (01:18:45)
Corrected entry: In the Shrieking Shack, just after Scabbers becomes Pettigrew, when Sirius and Lupin pull him out of the hole, as the camera faces Pettigrew's back while they hold him, the blue tape on his 'missing' finger is visible for 2 frames. (It is necessary to go frame-by-frame.) (01:31:30)
Corrected entry: In the very beginning, Harry is performing the Lumos spell in his bedroom. He's underage, therefore he should be well aware that he's breaking the secrecy rule and should have been alerted to the Ministry, yet they only take notice of him when he 'blows up' his aunt.
Corrected entry: When Dumbledore is studying the slashes on the portrait of the Fat Lady, you can see, especially well when the light shines on it, that the actual paining is extremely smooth. But a real paining would have at least some trace of paint brush strokes.
Corrected entry: When Professor Snape caught Harry missing the curfew, Professor Lupin came to intervene and save Harry from being punished. Lupin also took a parchment, the Marauder's Map, before Snape could confiscate it and asked Harry to come to his office. In his office Lupin mentioned to Harry that the map was a weapon for Sirius Black but he never asked Harry what is hidden inside the parchment nor did Harry ever mention a word about the map. Obviously Lupin should have had no knowledge about the Marauder's Map if he have never even heard anything about it. (01:17:40)
Corrected entry: When Harry and Hermione watched their past selves from the wood, there were some scenes where events happened too fast in second scenario. They see Lupin say "Immobilis" and the Whomping Willow stops moving, then just a few seconds later they see Snape coming. But the first time, Snape arrives in the Shrieking Shack few minutes after Lupin. Also Lupin transforming into a werewolf is too short in the second scenario. Hermione howls a few seconds after he changes, but the first time, Lupin transforms, then he fights with Sirius for about a minute.
Corrected entry: In the scene where Snape takes over the Defense against the dark arts class, (about werewolves) when the projector changes slides, on the screen the image moves clockwise at the top. However, when you see the projector, the light enabling a picture to be projected is on the bottom and the slides rotate counter clockwise.
Corrected entry: Hermione says that Harry wouldn't want to run into himself in the past, that he'll go mad. There have most likely been many instances when something like that would happen, a polyjuice user encountering the sample, for instance. It would probably cause confusion, but it's very unlikely that someone would go insane as a result.
Corrected entry: Platform Nine and Three Quarters is supposed to be a secret platform that only magical people can access. However when Harry, Ron and Hermione have boarded the train and are looking for a cabin we can see out of the window a GNER (Great North-Eastern Railway) train visible on the next platform. The train is most noticeable for its blue colour with a single red stripe running the length of the train.
Corrected entry: When the Dementors are boarding the train, everything starts to go cold, so much so that the water on the windows starts to freeze, and even more noticeably the water in the bottle completely freezes. Once the Dementors have gone, the windows are completely free from ice and the water in the bottle has melted again. This is not possible in the short space of time that passed.
Corrected entry: At the Leaky Cauldron a guy picks up a bottle and wraps a rag around it. A second later the bottle is gone.
Corrected entry: When the entire school is banqueting after their arrival, D. Malfoy says: "Potter. Is it true you fainted. I mean you actually fainted?" In the book, he found out because Neville was in the compartment as well, and he told "nearly everyone." But, in the film, only Harry, Hermione, Ron, and Professor Lupin are in the compartment. The three friends wouldn't have told them, and a schoolteacher doesn't go around telling such things to students. So, as Harry himself asked, how did Malfoy find out?