5th Jul 2012
Continuity mistake: After arriving in Hogsmeade, when Harry is talking to Aberforth Dumbledore, the table by the window has two chairs on one side of the table. A few minutes later, there's only one chair on that side, and the other chair is now at the end where there was previously none at all. (00:28:00)
21st Jul 2011
Other mistake: In both the books and the movies, Harry's Invisibility Cloak can always be seen until it is worn. In Diagon Alley, just before the Gringott's break-in, Ron pulls out the cloak to cover Harry and Griphook, but it turns invisible before he puts it on them. Ron merely mimes the motion of covering them.