Dr Wilson

Continuity mistake: During Hagrid's class, Vincent Crabe has his shirt outside his pants. He puts his things on the wall and when Draco and Harry are talking, his shirt is now half tucked into his pants. He didn't have the time to do that. (00:31:20)

Dr Wilson

Continuity mistake: When Aunt Marge flies off, she starts pulling the tablecloth and some food stays on the table but in each of the following shots where there's a view from the side, the table is clean. (00:04:55)

Dr Wilson

Other mistake: When Harry is talking with Arthur Weasley at the Leaky Cauldron, the number '301' (colored in white) digitally pops up right underneath the wanted poster. The composite people neglected to remove it. This mistake occurs in a DVD widescreen version, and not visible in all versions. (This is not referring to Sirius Black's number '390' written on the paper that Sirius holds in the poster). (00:16:50)

Dr Wilson

Continuity mistake: During the class with Hagrid, sometimes Ron has his Monster Book of Monsters under his arm and sometimes he doesn't have it. (00:33:35 - 00:34:55)

Dr Wilson

Continuity mistake: At the hotel, when Harry tries to catch the Monster Book of Monsters, a train passes and some wood powder falls from the ceiling but when Harry steps on the book, there's no more trace of powder on the floor. It can't be completely under the book, because there was powder at different places. (00:15:15)

Dr Wilson