Continuity mistake: 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.].
Continuity mistake: When Stifler's mom seduces Finch, you can clearly see Finch playing with the balls on the pool table. The camera cuts to another shot, and when it's back to Finch, the balls are back in the original place.
Continuity mistake: When Finch is moping through the house, depressed, he goes through a door marked "keep out". The door handle is on the left side, meaning that from inside the room the handle must be on the right. However, when he plays with the pool balls, we can see that the door he must just have come through (there's no other door visible) has the handle on the left.
Continuity mistake: Around the middle of the film, Oz's shirt changes going from the car park to the library, and then back again when he's singing in the classroom.
Visible crew/equipment: When Jim walks to Nadia the first time - right after he trips on the couch - a light stand is seen right at the left edge of the screen. This was pointed out in the DVD.
Audio problem: In the prom scene just before Heather is looking around and looking bored, the drummer is tapping on the hi hat, but the sound is a crash cymbal.
Character mistake: When Jim gets home and finds the apple pie on the counter with a note from his mother, the note reads "you're favorite", rather than "your".
Visible crew/equipment: When Finch is running to the toilet, a microphone wire is visible trailing down the inside of his shirt. This is pointed out in the DVD commentary.
Continuity mistake: When Nadia is going through Jim's drawer in his bedroom, a tub of Vaseline magically disappears from one shot to the next. In the same scene on top of the drawer a small white box appears at the same time the Vaseline disappears.
Continuity mistake: When Nadia goes to Jim's house, Jim throws all the porn stuff messily into a drawer quickly. A little later, when Nadia opens the drawer, all the stuff has been neatly positioned.
Audio problem: When Finch rolls the yellow 1-ball around the table, the first sound you hear is that of a ball hitting another ball, yet no other balls move. No balls are pocketed either - if a ball had been pocketed the yellow ball would have taken a different path around the table.
Revealing mistake: During the prom scene, especially during the song "(Don't You) Forget About Me", none of the band guys (especially the older man keyboard player) are actually playing their instruments.
Continuity mistake: In the famous Nadia on the internet segment, there is a quick shot of the computer before Jim starts to get undressed. If you look on the desk next to the keyboard there is a gray t-shirt. It wasn't there when Jim was setting up the camera and Jim hasn't begun to undress yet. Obviously shot after Jim threw the shirt on the Web cam and it slid off.
Continuity mistake: Finch runs into the girl's bathroom when the laxatives affect him. He tries to take out a toilet seat cover, but there are none left. The side shot shows a corner of the box hanging down below the dispenser, whereas when the shot changes to the front, there is no visible corner. It then returns to the side and the visible corner, and back to the front with no corner.
Audio problem: When the father gives the son the magazines, right before he's about to leave, he taps his hands together, but a loud CLAP is heard, like he really clapped his hands hard, while he just touched them together.
Continuity mistake: When Jim's father hands him the magazine "shaved" he changes between holding them at the top and at the bottom.
Deliberate mistake: When the father hands the porno mags to his son, if you look real carefully, you can see the son hide one of the covers from the camera with his hand.
Continuity mistake: When the boys are sitting in the living room talking about how they have to "do it" before graduation, one of the boys sitting on the couch has his legs crossed, then they uncross, cross,and uncross. They keep changing positions.
Other mistake: In the opening scene where Jim is watching the encoded TV and his mom comes in to say goodnight, after she kisses him if you look in the cracks of the shades it is light outside. It's day, not night.
Other mistake: When Jim is fooling around with Nadia, it shows a cameo appearance by Blink 182. It's obvious that the three people in this cameo are Mark Hoppus, Tom DeLonge, and Travis Barker. Travis Barker was the replacement drummer for Blink 182, when old drummer, Scott Raynor, left. Yet in the credits, it credits Scott Raynor, the ex-drummer, as being in the cameo.
Visible crew/equipment: In the Internet scene, Jim tosses his shirt over the webcam on top of the computer so nobody will see them. It shows one shot in Jim's bedroom of the shirt starting to slip off the computer, and the next shot is in Kevin's room seeing the shirt fall completely off. While they show the shot of the shirt falling through the computer, you can quite visibly see the hand that pulls the shirt off on the left side of the screen.
Continuity mistake: When Finch is at the party after the prom and he goes in the room with the sign on the door where Stifler's mom is he opens the door out. But at the end of the movie when Stifler is trying to get in the room there is a chair in front of the door and it opens the opposite way.
Continuity mistake: When Stifler and the girl are in the bedroom at his party, the amount of beer in the cup changes frequently. Before he picks it up, it's about 1/2 full, when he picks it up it's about 3/4 full.
Factual error: When Heather pulls up in her car and confronts Oz after seeing Stifler making fun of her on the Lacrosse field her car has an actual Michigan license plate on it. One of the producers even pointed it out on the DVD thinking that it was a great attention to detail. The only problem with that is the plate is on the front bumper. Michigan does not have licence plates on the front, only in the back.