During the drive-by shooting, Vaneeta pulls out a gun, but in the next scene, her hands are back under the table and there's no gun in sight.
In the scene where Shane tells Nancy that he was sent to the school psychiatrist for writing a "gangsta rap" depicting the death of a classmate, Nancy quotes the rap when she is scolding Shane, but she hadn't even seen the lyrics.
After the drive-by shooting, Conrad is seen sweeping the floor but his broom isn't touching the floor, which is visible under the table.