Audio problem: When they first enter the building they are going to use for the fake school, Bartleby tries to put a board back in the ceiling, and a body falls to the ground. Schrader screams, but the scream is heard before he actually opens his mouth. You don't see his mouth open until the camera pans into his character, but the scream is audible about a half-second before the camera movement.
Continuity mistake: During the accreditation scene at the end when Justin Long's character knocks down the chair after his speech, the camera angle changes and the chair is standing in front of him. When the angle changes again it's gone only to change the camera angle again and have one of the students put it upright finally in front of him.
Factual error: When the sprinklers go off during the S.H.I.T. party, Maurice yells "Wet T-shirt party!" into the mic and the DJ keeps playing with no problems. In reality, that amount of water would quickly destroy the audio equipment, and in all likelihood electrocute people as well.
Other mistake: When Bartleby is at the court room he said "Sunshine!" And the board of lessons comes in, but when the group entered to find out where there court room is, there's no evidence of them bringing the board in, and even if the student's brought it in, Bartleby wouldn't know the board was behind the door because he stated he didn't know the student's were coming.