Continuity mistake: When Scott is putting his books in his locker and is talking to Boof, he closes his locker. Then in the next shot, his locker is open.
Continuity mistake: At the very end, Pamela tells her boyfriend to drop dead and walks away, off to her right. But a second later, in the last shot where Scott is hugging his girlfriend and his dad, if you look just to the lower left of them, not only is Pamela still just standing there, but she's to the left of where she was standing before.
Continuity mistake: When Scott turns into the wolf for the first time in his bathroom, the position of his blue coat on the toilet seat keeps changing.
Continuity mistake: In the scene at the party, Scott is in a large group of mixed people doing party games. He's waiting for his turn to come and he's got wet hair. Yet when he and Boof are going into the closet, his hair is dry.
Continuity mistake: There is a scene where Scott and Stiles are talking in the garage. Stiles is standing in two different locations in the garage throughout the scene.