Plot hole: Harry never notices that the name "Peter Pettigrew" appears on the Marauder's Map, right next to "Ronald Weasley." Way beyond a character mistake, as there's no way that wouldn't be cause for interest. If nothing else, Ron's brothers who had the map for years before giving it to Harry, would most certainly have wondered why their brother was sleeping with a person named Peter Pettigrew.
Revealing mistake: At Hagrid's lesson, just after Malfoy wound Harry up, there is a close up on the class when they first see Buckbeak and you can see Emma Watson holding back a laugh. Surely if her friend was being picked on it wouldn't be funny, plus they're supposed to be scared of Buckbeak. (00:32:05)
Suggested correction: Not true. I saw this scene several times and I never saw Hermione holding back a laugh.
Suggested correction: JK Rowling explained why Ron's brothers didn't wonder why Ron was sleeping with a man named Peter Pettigrew. Here is the link: https://scifi.stackexchange.com/questions/11447/why-couldnt-harry-or-anybody-else-see-peter-pettigrew-aka-scabbers-on-the-marau.
jon snow