(at around 37 mins) When the piano falls down the staircase, it is straight, but later we see after the killer escapes from her house and Doofy is at the front door, behind Cindy the staircase is spiral.
(at around 15 mins) When the gang is in the car traveling around the curb in the "flashback," Greg stands up through the sunroof. When he climbs up to the sunroof his bottle of Jack Daniels is empty, in the next shot it is full.
(at around 18 mins) In the flashback, when Shorty is pulling up (car still moving, but nearing a stop) the inside of the car is clear (no smoke). As the car stops, the inside is completely filled with smoke.
(at around 16 mins) Greg's BMW 5-series hits something, breaking the driver's side headlamp, while the passenger side lamp stays on. Then when the BMW is on the dock, the driver's side high-beam lamp is shown as lit - which may be fine, but the passenger side low-beam is on.
(at around 45 mins) When Miss Mann gives the safety tips, an African-American girl stands behind her. That girl puts an article of clothing on, but she stops and leaves it curled up around her neck. The shot changes to the girls, then back to Miss Mann. This takes about four seconds. When it gets back to Miss Mann, the girl in the background is fully clothed and is standing relaxed and listening to the speech.
(at around 41 mins) When Buffy's mother comes into the room to tell Cindy she has a telephone call, her mother leaves the room. In the next shot when Cindy answers the phone, she is seen again standing in the room.
(at around 36 mins) When Cindy pushes the piano down the stairs, she is at the third floor of the house. She then runs down the hallway into her room, also on the third floor. She later runs out of the same door (you can see the third floor hallway in the background). Yet in the next shot, you see her running from her room, onto the second floor landing halfway down the stairs.
(at around 12 mins) When Greg is slamming his fist into the lockers you can clearly see the report card is the one use in the unedited WP. But when it cuts to the close-up its the version used in the final cut.
(at around 15 mins) In the flashback scene Greg stands up through the sun roof of the car. He is then seen being hit by trees as they pass him and his bottle of Jack Daniels is seen falling out of his hand and flying away. After they have hit the man and they're standing outside the car he is then seen with the bottle of Jack Daniels again.
(at around 46 mins) When Cindy has her meeting with Miss Mann, it's following lunch time at school (as she's wearing the same outfit), however, the clock on the wall in Miss Mann's office points to the time being 9:50.
(at around 12 mins) When Buffy and Cindy are walking together in the school corridor, Heather hands a yellow sheet to Buffy, in the next scene where they meet Greg and Ray, the yellow sheet disappears and is replaced by a colorful magazine and a banana.
(at around 16 mins) After the group hit someone in the car, the car stops partially over the yellow lines in the middle of the road. In the next shot the car has come to a stop a few feet to the side of the yellow lines.
(at around 16 mins) After Greg complains to Bobby about the damage to his car after they hit someone, he is holding only a bottle of Jack Daniels. After he realizes that they hit a body he is holding a torch.
(at around 28 mins) When Greg shows the nude picture to the others, Brenda, Cindy and Buffy start laughing at it. The next scene, however, shows Buffy applying makeup and has moved away to the side of the frame.
(at around 11 mins) When we are viewing Gail Hailstorm reporting the incident at the school, there is someone sitting in the tree behind her, in the next shot where the camera pans around all the other news reporters the person has disappeared from the tree.
(at around 1h 14 mins) During one of the last scenes when the Killer throws Cindy against the wall, the wall dents in and the killer then damages the table below and knocks a picture down leaning against the wall. A few shots later, a chair appears in the same place and the killer uses it to click his back into place.
(at around 1h 17 mins) During one of the last scenes when Doofy hands over a blue folder covered with jam to the Sheriff, it is closed. However in the next shot, the folder is open and the Sheriff is looking through it.
(at around 12 mins) Ray asks Greg if his yellow shirt makes him look gay. Then the camera cuts away; when it cuts back, Ray is wearing a black t-shirt instead of the yellow one he just had on because he put it on over the yellow one.
(at around 1h 13 mins) After Ray and Bobby reveal that they are copycats, the killer stabs Ray and the hook does not come through his chest. In the next shot it has come through his chest and he is bleeding through the hole; in the next shot, the blood and hole have disappeared again.
(at around 1h 10 mins) When Ray and Bobby are talking about killing Cindy and her father they trade weapons. But when Ray goes to get Cindy's dad he no longer has the gun. Later when Ray is going to kill Bobby the gun is not on the counter. So he could not have set it down.
(at around 1h 13 mins) While Ray is explaining to Cindy about television shows creating psychopathic killers and when he starts stabbing Bobby, the knife is in his left hand, but in the next shot, he's stabbing Bobby with the knife in his right hand.