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.
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.
After Drew hits the trick-or-treaters with the bat, you can see a paper skeleton on the outside of the front door. However, in the next shot, the skeleton is seen on the door to the right of the front door.
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.
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.
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.
When Buffy and Cindy are walking together in the school corridor, Heather hands a yellow book to Buffy, in the next scene where they meet Greg and Ray, the yellow book disappears and is replaced by a colorful magazine and a banana.
After the group hit someone in the car, the 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.
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.
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.
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.
The goof items below may give away important plot points.
In the scene where 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.
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.
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.