In the bedroom scene the girl is holding a clear cup full of beer. The camera goes off her and when it comes back she is holding a blue cup. The camera goes back off her then on her and the cup is clear again. [This mistake does not appear in the unrated version - the blue cup scenes were shot specifically to secure an R rating from the MPAA because the contents are obscured.].
A little trivia for the American-Pie-Movies fans: The movie is obviously based in Michigan, as apparent by the dialogue of the characters and the frequent mention and appearance of such schools as the University of Michigan and Michigan State University. What most people don't realize, is that the characters live in a town called "Great Falls", which is based on the writer's hometown, Grand Rapids. Those of us fans who live in Grand Rapids, Michigan have so much fun with these movies because they contain one hidden reference to our town after another. For instance, the kids go to East Great Falls High School. One of the biggest and most preppy schools in the area is East Grand Rapids High. Also, the hotdog shop that the guys frequent, "Yesteryears", is a real place: only we call it "Yesterdog" and it's been a very popular hangout for almost 50 years. In the sequel, the guys go to Grand Harbor, a resort town by the lake. This is a place based on a town on Lake Michigan called Grand Haven. Many of us who live in Grand Rapids actually do this very thing during the summers. There are again, many references to Grand Haven (and Grand Rapids again) in the sequel, but the movie does short the audience on one thing: one of Grand Haven's highlights is a fantastic pier and lighthouse. The lighthouse that Jim and Nadia go to is pathetic in comparison. If you ever have the pleasure of visiting West Michigan, and are so inclined, be sure to watch the movies with a native and then visit the real locations.