Continuity mistake: How come everyone including Randy had their jackets on and appeared to be leaving the party and yet Randy was the only one left at the party at the end, before the bloodbath? The answer to this spawns another goof itself: Randy said he'd stay behind to check on Billy and Sydney, which is why he didn't leave. However, the goof is that he didn't actually go upstairs to check at any time, because he'd either have seen them having sex, or else found Billy's body. Of course, another explanation is that we're made to think that Randy must be the killer, because he's the only one who stayed behind. We just don't know.....
Factual error: Gale Weathers points the gun at Billy and tries to shoot him, but the trigger doesn't pull back. This is explained by Billy when he says that the safety was on. Fine. But that gun is a Beretta 92F, and on a Beretta 92F when the safety is on, the trigger WILL pull back, but no round will fire.AidanN
Revealing mistake: When they shoot the killer at the end, the hole in his head is there before the gun goes off. You can see the hole in his head for about a frame before the flash of the gun goes off and his head drops. The body is also clearly a dummy. The scene then cuts and they show him being shot again. Once more, the wound is already there.
Continuity mistake: After the girl's dad leaves the room, Billy holds up a red stuffed bear against the bed. In this shot, the bear is only half sticking up at about its arm level, but in the next cut, it's high enough its feet are visible on the bed. Then only a second later as Billy starts to stand up, a jump cut has his arms go from down to outstretched with the bear instantly as he starts to stand.Quantom X
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.
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.
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.
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."
Factual error: After Gale talks to Sidney and Sidney seems doubtful of Cotton Weary's guilt, Kenny the Cameraman says to Gale, "Do you wanna go live?". Gale is an anchor/reporter for a tabloid-like show called "Top Story" (Sort of like "Current Affair", "Inside Edition", or "Hard Copy"). She does not work for CBS News or NBC News, etc. She does not have the power to "go live" and interrupt regular television programming. (00:41:55)
Continuity mistake: Sidney is on the roof trying to escape from the killer and she falls off. When she gets up she sees the dead body of Tatum in the cat door and her left arm must be behind her because you can't see it but this isn't what happened when you saw her die. Her left arm was inside the garage and was beside her. Unless if fell off, it should be next to her body.
Other mistake: When Sidney is preparing to go to Tatum's house, she brings several items of clothing downstairs, including a pair of boots, which seem to be knee-length from the way she is holding them to her chest. However later when she is dressing after her session of nooky with Billy, the boots have changed to ankle length. [The clothes that Sidney packed were in the house and she never got them since she left the house after she was attacked and besides the day that she made nooky with Billy was a different day then the day she was attacked.]
Continuity mistake: When the cameraman is watching the 30 second delay footage and the ghost face is about to kill Randy who is on the sofa, he walks into the room in a different way on the delayed footage to on the actual film footage.
Continuity mistake: After Courtney Cox runs to the van when she's being chased, she hops into the van and throws it into reverse, guns it, then slams on the brakes, and the body falls down onto the windshield. Slamming on the brakes after going in reverse would cause the body to fall the other way, toward the back of the van. (01:22:50)