During the conference of the four boys at prom, there is a close-up of Kevin Myers speaking. However, in the next shot they show Oz, and in the corner is part of Kevin's face mouthing the words he had just spoken.
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.
When Vicky comes over to Kevin and Jim at the party Stifler, who was standing behind Jim, walks away. When we next cut to Jim, Stifler is standing in the same position despite having walked away a few seconds earlier.
When Kevin and Vicky get to their room, Kevin starts taking out candles from the drawer on the nightstand. When they are lying in bed, the candles are lit, when they are getting started, the candles are still lit, but during the last shot, the candles are nowhere to be seen.
The QuickCam has been glued at a 45-degree rotated angle in its base, as evidenced by the visible tripod mounting bracket normally hidden down in the base; however, it still produces rightside-up images.
When Vicky and Kevin are sitting on the bed he hands her a cup of beer which is in a clear cup, but for one shot it is blue. This also happens when Stifler comes into room afterwards and the cup is in Sarah's hand. The cup goes from clear to blue and back to clear depending on the right/left camera angle.
Jim is changing position between shots when he is preparing to approach Nadia at Stifler's party, despite the fact that he is standing all the time. You can see it if you pay attention to picture and flowers behind him.
When Noah hands Jim the third porn magazine, the first couple of shots show his hands at the top of the magazine. In the next shot, when Jim takes it from him, Noah's hands are at the bottom of the magazine.
During the first lacrosse game you can see Mexican Fan palms in the background. These are the famous palms all over Beverly Hills. They are everywhere in Southern California, but do not grow in Michigan.
The camera broadcast of Nadia is being displayed in a total different operating system. Behind the camera it looks like Mac OS 8, however the window in which her camera stream is being shown in, is Irix. (at around 1h 30 mins)
While Jim, Finch and Kevin are watching the webcast of Nadia, there are dates available on the screen, all referring to the month of July. However, being in school and preparing for prom, it would have most likely been April.
When oz gets dumped by Heather out by her car, he is wearing a white t shirt. In the next scene in the library he is wearing a dark blue t shirt. When he's in choir class in the next scene he's wearing the white t shirt again.