Revealing mistake: When the boys drive the car over the gap in the bridge, look at the side view that shows the main jump, watch the front wheels, they lift up in the air unnaturally before the car leaves the ramp. (00:34:00)
Continuity mistake: The college is supposed to be Ithaca University, but in the stadium scene they fail to cover up the University of Georgia "G" in the middle of the field. There are also times when they are supposedly in other states but they are obviously in Georgia the whole time..
Continuity mistake: When we first see the padded envelope, Josh has put three stamps on it, spaced out. Then when he finally retrieves it, there are 8 stamps. Admittedly his friend might have replaced them with the correct postage, unlikely though it is, but unforgivably, the address is completely different - most noticeable is the middle line. The first time it's "5893 Tyler", and the second time it's "695 University Dr." The sender's address also changes from "Columbus St." to "549 Campus Drive".
Continuity mistake: When the band is playing in the background at El's house you can clearly see that one of the band members has a cigar in their mouth, but when the camera cuts to the band playing the cigar is gone.
Continuity mistake: Twice towards the end of the film (as we see the bus arriving at Austin, then also as it arrives back home) the bus has a front number plate (clearly visible on the front bumper during the montage driving shots), then soon afterwards it disappears.
Revealing mistake: When Barry is feeding the snake there is some sort of plastic over its mouth. (00:51:00)
Continuity mistake: When they jump the bridge they land on the left side of road (right side of the screen) when they show the shot of them walking away the car is on the right side of the road (left side of the screen).
Continuity mistake: When Tom Green is playing the guitar (after the mouse has been dropped in and the snake's head is somewhat near it) the hand with which he plays the guitar switches several times as the view of his face switches. When it's a profile view, he strums on the neck of the guitar with his left hand. When it's a straight view, he plays the bottom of the guitar with his right hand.
Continuity mistake: In the scene where Josh is having the dream that Tiffany is watching the tape with her friends, when the camera zooms in on Tiffany as the movie is playing, look behind her head in the mirror and you will see the movie scene where Beth walks towards Josh in her underwear. It then goes to the television, where it plays the same scene again, then continues.
Factual error: The envelope sent to Austin, Texas has the ZIP code 50321. This is a zip code for Des Moines, Iowa. All Austin ZIP codes start in 78.
Continuity mistake: Not only does Josh only put three stamps on the letter and at the end and in the dream sequence it has eight, but in fact in the same scene (at the beginning where he actually puts the stamps on), the number of stamps changes from three to eight with only a few seconds in between.
Factual error: In the scene where the guys are in the cafe, the waiter pours coffee, then puts his hand underneath the hot coffee pot. You cannot do that with a true glass coffee pot if your coffee is hot. (00:43:30)