In the scene where Stegman and his gang go to the punk band club, the punk band Teenage Head are playing. The song that the band is playing is called "Got No Sense". Before Stegman gets on stage to stage dive, he gives a two fingered gesture to the crowd. The singer of the band onstage is next to Stegman singing the song, but his lips are not matching to the words of the song being played by the band.
When the thug climbs up the flag pole, he is alternately holding/not holding the flag in his hands.
When Terry points the gun at the thug student, its distance from the thug's face keeps changing.
When Perry puts the thug's arm on the table saw, the amount of blood, and its position, changes, depending on the shot.
When Sally auditions for Peter Stegman, the far shots show her wearing some kind of decoration around her neck, while the close-up shots show her neck bare.
There is a visible pad under Mr Norris's shirt, as he is beaten up.
When Norris cuts the arm off the thug on the table saw, blood is clearly shown spattering into the left armpit of his white shirt. After he leaves the shop and is running in the hallway, the white shirt has no blood in that area.