Other mistake: The envelope with the letter for Amanda is suddenly in a very good condition as it ends up in the peanut bowl... even though it has been in the trash, had chewing gum attached to it, been trodden on, had a beer barrel rolled over it, etc....
Continuity mistake: When the two X-philes are getting on top of the poolhouse roof, you can see a microphone angling itself back and forth between characters as they say their lines.
Continuity mistake: When LoveBurger leaves the stage, a raucous teen jumps onstage and blares Paradise City from his boombox. William recognises the song and jumps over to the stage. When he jumps on, he knocks the other guy over. Watch as the other guy falls off the stage, as a microphone on top of the stage falls over and smacks the camera at the top of the screen.
Continuity mistake: When we see William's yearbook information it actually looks as if he has loads of activities yet if you watch it in slow motion the same list of activities are repeated at least three times. Also, it says he was a member of the "Large Wooden Club".
Continuity mistake: When William is handed his first beer, it is only half full. When he takes the first drink, the glass is about three-quarters full and when he takes the second drink after he spits out the first, the glass is completely full to the rim.
Continuity mistake: As the letter to Amanda from Preston is being dragged through all that trash, it is stuck to a metal tin that someone was rolling by. The letter falls off a second later but when the camera angle changes it is again stuck to the tin and then falls off again.
Continuity mistake: When Kenny goes on the long line for the bathroom downstairs, like 50 girls cut and run into the bathroom. If you look carefully the same girl runs in twice. Shes tall, has short hair, and is wearing a brownish colour dress.
Continuity mistake: When Preston is about to talk to Amanda on the couch and when he kicks over the candles, before he kicks them over you can see that there are only 2 or 3 candles. When he sets them back up, you can see that there are 5 or 6 candles.
Continuity mistake: When Preston and Denise are sitting on the hood of the car talking, one of them moves and you can clearly see the tape mark where they were supposed to sit.
Continuity mistake: At the party, before Amanda gets there, her friends are talking and when one of the girls says, "Oh my god, I can't believe she came!" (when Amanda comes in) You can see her mouthing the same line, when the camera goes to a different angle.
Continuity mistake: When Seth Green first walks into the bathroom he takes his coat off but in the very next scene he still has it on.
Continuity mistake: When Seth Green and Lauren Ambrose are making up right after the party in one angle her bangs are down and in another angle her bangs are up.
Other mistake: When the girl throws the brownie at Denise, it is apparent that the chocolate gets into her red hair, but in the next shot when Denise enters the bathroom, the chocolate has mysteriously moved to her cheek and her hair was clean.
Continuity mistake: When Preston and Denise are in the car driving to the party Preston appears to be only wearing a shirt yet when you see him later he is obviously wearing a t-shirt underneath.
Continuity mistake: In the beginning when Preston is talking to Denise about when he first met Amanda, he says she was eating a Pop-Tart. You can see when she is leaving, the pop-tart is near the centre of the desk, but it shows it falling off when no one ever touched it.
Continuity mistake: When Mike goes with the two girls who said he was the hottest guy in school and they say he said they were skanky, they were sitting on a bench, and at the next scene he appears sitting on a swing. [It is both a swing and a bench. If you watch Mike sit down, you can clearly see that it is a swinging bench-type chair.]
Continuity mistake: After Mike apologizes to William for humiliating him at graduation, William forgives him and they toast their wine. In the wide shot, Mike puts his wine bottle down on the piano. In the close-up, he is still holding it.
Answer: The filmakers decided to forego showing Amanda's face early on to give her grand entrance at the party more impact.