Continuity mistake: When Tatum calls Sidney at 7:15, she reaches over to get the phone. The sleeve is at her elbow in one camera angle, but it's instantly at her wrist in the shots before and after. (00:25:15)

Continuity mistake: When Sidney is talking to Tatum and Stu by the lockers, the combination locks she's standing by are black in a closeup, but when a student runs past in a scream costume, she is by lockers with a pink and a turquoise colour lock. (00:40:50)
Continuity mistake: When all the guys are sat outside of the school talking about who (a male or a female) is the murderer, Tatum's leg is behind Stu's leg. In that same action, we go to a close up and suddenly Tatum's leg is in front of Stu's leg. (00:19:55)
Continuity mistake: When the killer sneaks up on Randy, Randy is lying back against the sofa. When Ghostface raises the knife Randy is lying back, relaxed with a tired look on his face. On the delayed footage when the killer raises the knife, Randy leans forward and is practically on the edge of the seat, his mouth and eyes wide open. (01:22:55 - 01:23:30)

Continuity mistake: When Tatum goes into the garage before she gets killed,she goes to get beer. She then walks over to the garage door opener with the beer in her right hand. Her left hand is reaching up to push the button, but as they show the close up, it is her right hand pushing the button. (01:05:35)
Continuity mistake: In the scene where Tatum gets closed in the garage door, the first time it shows her arm hanging down. In the next scene, it shows her arm caught in the door. (01:07:30 - 01:22:15)
Continuity mistake: After her first time with Billy, Sid brushes her hair. She puts the brush back on the bedstand, but the phone on it changes angle between shots. Later in the scene, you can also see the brush's handle sticking out from the side of the bedstand by the bed, or the one facing front. (01:18:55)
Continuity mistake: When Skeet is first shot by Gale he crawls backward, but if you look at the ghost face behind him there is no knife there. The next shot there is a knife on top of the ghost face.
Suggested correction: There is no 'next shot' showing the ghost face following the backward crawl. The next time we see the ghost mask is when Sidney headshots the killer, which is a mistake already pointed out in a separate entry (#326576).
Continuity mistake: After the killer calls Casey the second time she puts a salt shaker on the counter, she walks round to her living room, and the killer phones her two more times. When she gets back to the kitchen the salt shaker has disappeared.
Continuity mistake: When the whole gang is watching Halloween, they see the scene in which Michael Myers impales a victim with a knife, which suspends him from the wall. Just before Randy pauses the movie, Michael Myers is standing and admiring his handiwork. When Randy pauses it, the frame is of Michael Myers raising the knife, which of course, happened 10-15 seconds ago.
Continuity mistake: The first time that Casey Becker is stabbed by the ghostface, you can see the knife go into her chest, very deeply, but no blood is there, but directly in the next shot, her shirt is covered in blood. (00:10:50)
Continuity mistake: When Stu puts the voice box and phone in Sidney's dad's jacket pocket and lets him fall, when he hits the ground the voice box partly falls out, but then when they show the dad again the voice box is tucked back in.
Continuity mistake: When Randy explains the "Rules" to everyone and mentions the rule of no sex only two guys throw popcorn at him. Also they only throw one piece at a time, yet when Randy says "Big nono, big nono" you can see bucket loads of popcorn flying at him. (01:13:20)
Continuity mistake: When Randy is explaining the rules of a horror movie to the people at the party he pauses the movie and says "Jesus Christ you don't know the rules?" When the camera guy is in his van later we hear this audio again on the recorder but instead Randy just says "You don't know the rules." (01:13:00 - 01:14:00)
Continuity mistake: When Casey puts the two videos on top of the TV, she puts them on top of each other so they are placed neatly. Then when she picks up the letter opener off the TV later, the videos are no longer stacked neatly. (00:08:10)
Suggested correction: To be fair, we don't see (at least in the DVD version I am looking at?) the VHS boxes for the entirety of the time her hand is on it, and she does bump against the TV set at least twice while talking to the killer, once with the top of the set entirely off-camera.
I would say it's a valid mistake because we do see a shot of the tapes later, and they're still neatly placed (for example, when she says her boyfriend will be there any second), so we know she didn't do anything to them when her hand was off camera. And I never saw any bump hard enough after her boyfriend is killed that would move the top case into the new position it's in.
Continuity mistake: At the party at Stu's house, when Dep. Dewey is walking through the house looking for the killer, Dewey walks into the living room with the TV and couch. Look at the TV, there is a white phone sitting right next to it. Later, when Sydney and Stu are fighting and she is about to push the TV on top of him, the white phone is gone. The TV also appears to be bigger. (01:40:40)
Continuity mistake: Mr. Himbry calls the two expelled students "Desensitized little sh*ts", pointing the open scissors at him. In the next shot he's looking at him but he changed position, since the scissors are gone from frame. (00:45:20)
Continuity mistake: Gale falls back on the unconscious Dewey after Billy kicks her. Her jacket is draped across the chest touching the white button of her vest. When Billy gets on his knees by her though, the jacket is fully open. (01:37:30)
Continuity mistake: Once Billy is done slashing his accomplice, he points the knife at him and tells him what to do; the knife hand keeps changing position between shots. (01:36:00)
Continuity mistake: Plummeting from the roof onto a boat, Sid causes a wetsuit (or a similar kind of fabric) to fall off. In the closer shot, the cloth is much more entangled than in the other view - look at the pink band. (01:21:55)