Warwick Davis character, Professor Flitwick, is not mentioned in Prisoner of Azkaban. He is listed in the credits simply as Wizard. Director Alfonso Cuarón came up with the idea of having him play the choir director. Goblet of Fire director Mike Newell liked the new look, and it became Davis/Flitwicks look for all of the subsequent films. It meant a lot less time in the makeup chair as well, but he made up for that when he played Griphook in Deathly Hallows.
27. Your CGI-generated Character "Ewwww" Moment
During Hagrid's first Care of Magical Creatures class, Harry has been "volunteered" by his fellow classmates to be the first one to meet Buckbeak, the hippogriff. Just after Ron pushes Harry forward, Buckbeak casually drops a load, just like a horse. It's hard to tell, even on Blu-ray, but it appears to be orange in color. Guess dead ferrets are high in iron.
26. Fun With Foreshadowing
While Harry is approaching Buckbeak, Hermione at first grasps Ron's arm, then his hand in fright. Reportedly, series author J.K. Rowling complimented Director Alfonso Cuarón on his foresight into the future Ron-Hermione relationship. Of course, Rowling recently announced that she regretted pairing Hermione and Ron, but if she hadn't, it would have queered everything she had done to set up Harry and Ginny's relationship.
25. Wizards Don't Do Spell Check
When the Weasley twins show Harry how to open the Marauders Map, the name "Moony" is spelled "Mooney" but it's not a matter of a spelling mistake. The film's visual effects supervisor is Karl Mooney. The spelling was changed deliberately as an inside ioke. But it's not as bad as the one that shows during the end credits. (Look up the aforementioned Easter Egg article for that.)