Continuity: When Denise is hit with the brownie it leaves chocolate in her hair, but later in the bathroom it is on her face.
Continuity: When Kenny enters the upstairs bathroom, he removes his backpack and takes a look in the mirror. His reflection shows him not only without his backpack, but in that split second he somehow loses his jacket as well.
Crew or equipment visible: Actor's mark visible on the floor at the train station when Amanda leaves Preston.
Continuity: In the final scene at the train station, Preston drops his luggage to run to Amanda. In the wide shot that follows, his luggage is gone.
Continuity: Amanda's hair in the final scene at the train station falls out of her hair clip between shots.
Continuity: When Amanda takes a bite of the strawberry pop-tart, she places it back on the middle of the desk. When the camera returns, the pop-tart is at the end of the desk and falls off.
Continuity: The direction and intensity of the lighting changes constantly during the bathroom scenes.
Errors in geography: The movie is set in Pennsylvania, but the train station used for the finale is very obviously Union Station in Los Angeles
Continuity: The letter clearly falls off the beer keg, but in the next scene it is still stuck firmly.
Continuity: When William goes into the house and gets a beer, he takes a sip from a half full glass and spits it out. Almost immediately after, he takes another sip, and the cup is almost full.
Continuity: When Amanda is trying to figure out who Preston is, a girl in yellow tights walks past in the background twice.
Continuity: The position of the hand towels in the bathroom when Denise and Kenny are locked in.
Continuity: When Kenny goes to use the bathroom there is a long line. A girl wearing a long, sparkling, tan dress is seen running into the bathroom twice.
Crew or equipment visible: Actor's mark visible when Denise and Preston are sitting on Preston's car outside the restaurant on the morning after the party.
Continuity: Both Preston and Denise's hair are notably shorter the morning after the party.
Continuity: When Amanda comes down the stairs her hair is done. In the next shot when she reaches the bottom of the stairs coming in to the yard, her hair is very flat. Then Preston says "Amanda, I love you" she turns around and her hair is done again.
Continuity: In the scene where Kenny and Denise are talking in the street, every time the camera is on Denise her bangs are on her face, but every time the camera is on Kenny, her bangs are off her face and pushed back.
Revealing mistakes: When Preston looses hope after seeing Amanda being kissed by her cousin he tosses the letter he wrote to Amanda in the garbage, you see a silver Honda Civic next to the trash cans. The Brake lights and third light are flashing, it was done in a rhythmic pattern to make it look like the hazard lights are on. In reality the only way to make this happen would be to have someone continuously pump the brakes. The hazard lights on that make and model would be the lights below the brake lights and would flash orange in the same rhythmic pattern.