Continuity mistake: When Ray tells Brenda to put on his football gear, he hands Brenda his shoulder pads. When Brenda accepts these she has two braids hanging down in front of her. The camera cuts to Ray for a second then back to Brenda. When the camera has cut back the two braids have moved over her shoulder. She couldn't have moved them with her hands as she is holding Ray's shoulder pads with both hands. (00:49:30)
Continuity mistake: In the scene when Ray goes to the restroom while at the theater there are men urine racing.There are five urinals. The man with the white hat is to left. The man with a black cap is to the far right.when the third man from the left is declared winner.The man with the white hat shifts right one space and the man with the black hat takes his old spot. (00:55:45)
Continuity mistake: In the scene where there's a party at Cindy's house, two kids behind her are drinking liquor out of bottles that are completely upside-down, but the level of liquid remains constant. (00:57:00)
Continuity mistake: Just after Brenda drops the first beer bottle, her hands are out in the "don't shoot" position. The camera cuts and she is holding the bottle in both hands. (00:57:50)
Continuity mistake: In the scene in the bedroom between Cindy and Bobby, just before he explains about sucking on a tootsie pop, Cindy's hair is all messed up. Camera cuts and it is fairly different. (01:02:15)
Continuity mistake: Near the end of the movie, when Ray is stabbing Bobby, Cindy says "You've watched one too many TV shows." Ray points the knife at her. At this point the knife is in his left hand but when he turns back round to stab Bobby again the knife is back in his right hand. There is not enough time for him to swap hands between shots. (01:10:25)
Continuity mistake: When the killer jumps up behind Ray and stabs him through the back with the hook, we see he obviously gets lots of blood on it. Watch it when he goes to stab Cindy and misses. It hits the cupboard and is completely clean. The hook is clean for the rest of the time he has it. (01:10:50)
Continuity mistake: In the scene where Ray is killed, the killer stabs Ray with his hook. Ray's shirt is not bloody, but as he falls it is. Then when he lands on top of Bobby his shirt once more is clean. (01:10:50)
Continuity mistake: At the end of the Matrix scene he throws Cindy into the wall, look when she hits the wall there is no sign of hitting the wall, but when she is falling to the ground they is an imprint like an oval on the wall. (01:11:05)
Continuity mistake: In the scene where Cindy was fighting the killer Matrix style, she threw a brass ornament at the killer like a Frisbee and the killer dodged it, and the brass ornament should have gone out of the window by smashing through it. But the window was broken by the killer flying out of the window after Cindy kicked him/her. The brass ornament has mysteriously disappeared into thin air. (01:11:40)
Continuity mistake: When Cindy has kicked the killer out of the window she runs over to her dad. His hands are supposed to be tied, but the ties are actually already loose. (01:12:35)
Continuity mistake: When Cindy is fighting the killer during the Matrix spoof, there is a short, storage table to the right of the plaid curtains. When the killer flies backwards through the window, that table is to the left of the curtains. (01:14:00)
Continuity mistake: After the killer throws Cindy at the wall and then breaks the long table, Cindy runs and stands in front of the round side table and lamp, which are right beside the wicker chair. However, when she levitates, that table and lamp are now beside the couch.
Continuity mistake: When Buffy comes up to Greg and he is banging his fist up against the locker and cussing, you see his report card in on hand and you can see the outlining of the subjects but there is no "DUMB-ASS" stamp on it, but in the close-up there is.
Continuity mistake: When Bobby spews out, ahem, "the white stuff," it is all over the ceiling, but when it cuts back to Cindy and Bobby, it's not on the ceiling anymore.
Continuity mistake: The living-room in Cindy's house has wood plank flooring, which is perpendicular to the plank flooring in the hallway, as seen at the doorway when she runs down the stairs and locks the front door. However, when she runs up the stairs as the killer chases her, the living-room wood flooring at that doorway is gone.
Continuity mistake: When Cindy and Bobby are talking in the school cafeteria after he gets out from jail, the students in the background keep disappearing as they go off camera from shot to shot when they should be seen walking away behind the characters.
Continuity mistake: When Bobby and Cindy slowly begin to make-out on her bed there is a TV set behind them, but after Bobby gets his finger shocked on Cindy's "underwear" and the both of them get up to leave, the TV set is gone.
Continuity mistake: When Drew goes to answer the door to the trick-or-treaters, the shot of the table at the front door has four legs at the corners. When the close up shot of it is taken, it's now a totally different table with a single middle post.
Continuity mistake: During the final confrontation scene between Cindy, Bobby and Ray, watch the knife that Ray holds. During close-ups it's a hunting knife with a fairly large blade. However, during a couple of the long shots, the knife blade is a different style and much shorter, obviously the prop knife used for the stabbings.
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.