During the shootout prank scene, the brown getaway van clearly shows no number plates on the car. Later in the movie when the sheriff arrives, a student gives the sheriff a license plate number.
Lisa asks two boys to carry down her luggage in an early scene at the dorm rooms, including a large yellow suitcase. Later, Lisa pulls the same suitcase from under her bed and packs it again.
Wildman's grip on the pledge who stole the exam changes between shots.
When he's discussing speed Wildman's face goes from clean to having cream around his mouth between shots.
When Mark is killed he is walking and is behind the third barrel and the killer starts jumping out. The point of view then changes to behind the killer who stabs Mark and he falls down beside the first barrel. During the change in point of view Mark has somehow instantly jumped forward 4-5 feet. The killer would not have been able to reach him.
Around the 21 minute mark, as Gary is leaving the cafeteria with his frat brother, you can clearly see the camera and boom operators in the reflection of the glass door.
When the sheriff's car pulls up to the group of students after having been called to respond to the "mass murders" (but what turned out to be nothing more than a fraternity prank), the insignia on his car door says "Cherokee County", yet the patch on his uniform's shoulder says "Cleveland County". Incidentally, those two counties actually do exist in North Carolina where the movie was filmed, but they are geographically a considerable distance apart.