Visible crew/equipment: In the beginning of the movie in the scene where Cindy and Bobby are in Cindy's bedroom,the Dawson's Creek theme song just starts to play and in the bottom left hand side of the window, just before Dawson pops up and says "Wrong set" you will notice someone dressed in black start to creep up for a second, then Dawson pops up. (00:07:15)
Visible crew/equipment: When the teens are all standing out side and the teacher is ready to jump from the school building. As he is jumping you can see the shadow of the scaffold he jumped from in the left bottom hand corner of the screen. (00:48:20)
Visible crew/equipment: After the garage door comes down on the garage victim, a hand can be seen from the outside pushing her boot off her foot as she's frantically kicking her feet.
Visible crew/equipment: During the Matrix send-up, after Cindy throws the platter at the killer, an actor's T-mark is visible on the floor, when he leans back and flounders about.
Visible crew/equipment: At the start, just before Drew grabs the banana, a boom mic is in view in the window behind her.
Chosen answer: I know for sure they were making fun of the movie 'Usual Suspects' (dropping the cup) - they might have added the gag of the fish in it to appear as though she was shocked by the fish instead of the true identity of Doofy.