Continuity mistake: When the killer pops out from the closet after Sidney closed the front door, he's holding the knife above his head, but it cuts then to a shot of him raising the hand from a position below the waist. (00:28:35)
Continuity mistake: The gang is chatting about the murders and their interrogations. Stu responds "There's no way a girl could have killed them" to Tatum's complaint that nobody asked her if she likes to hunt. In these two shots, Rose McGowan's hair is wildly different. (00:20:00)
Continuity mistake: When Tatum asks "Why would they ask you if you like to hunt?" look at the blue backpack. Next shot, and the light is on it in a different position than before. The position of the various actors as they eat grapes also changes. (00:19:50)
Continuity mistake: When Billy tells Sidney that her mother is the reason his parents split, he's pointing the knife at her, but not anymore in the reverse shot. (01:33:00)
Continuity mistake: Look at Matthew Lillard once Billy says "What's the matter, Sidney? Looks like you've seen a ghost." He's scratching his cheek, but in the next shot his arm is down his side. (01:31:15)
Continuity mistake: Billy's expression is entirely different in the two shots when he raises his gun and points it at Randy. (01:30:25)
Continuity mistake: In the scene at the TV truck, the killer's knife is blood-free even after slicing the cameraman's throat and stabbing Sidney, if you look at him when he tries to open the door and when he gets in. When he shakes his fist at Sidney for running away though, the knife is all bloodied up. (01:24:00)
Continuity mistake: When the killer slits Kenny's throat, Sidney in the background stifles a shout with one hand on her mouth, both hands in the next shot. She opens her hands but her right hand is still glued to her face in a further cut. (01:23:40)
Continuity mistake: When Kenny the cameraman spots the front door open and turns around to look again at the truck, Sidney before the camera cuts away is turning all the way to look at the monitor as well, but in the next shot she's still facing Kenny. (01:23:35)
Continuity mistake: Randy pauses the movie and gets up to explain "the rules." Stu comments "Have an aneurysm, why don't ya?" Matthew Lillard's hand is in a different position in that shot. Not only that; the only extra you can partially see on the right in the background, in the previous shot made a disappointed gesture and lowered his arm, and in this new shot he lowers it again anew. (01:13:05)
Continuity mistake: When Sid and Billy make out and talk about Meg Ryan and other kinds of movies, their hands go on and off the back of their heads between shots. (01:11:00)
Continuity mistake: The killer is holding the knife he uses to cut Tatum at an angle that changes between shots when he's threatening her. (01:06:25)
Continuity mistake: In the garage scene, Tatum grabs 5 bottles of beer. She initially has 4 of them in her right hand, a single one in her left, and in fact she can easily reach the fridge door and close it with that hand. New shot, and she is not closing the door anymore with her left hand, suddenly busy with the other bottles, and she has to use her foot. (01:05:05)
Continuity mistake: When Gale makes her entrance in the room with all the teenagers at the party, look at her position in particular in relation with Matthew Lillard; she wouldn't pass Sidney by in the spot when it happens, and she approaches him in different positions. (01:03:50)
Continuity mistake: Gale and her crewmember just arrived at the party location. He asks if they have been spotted, she says no, and he then sinks back into the van to fetch the equipment. The shot changes and he completely turned around. (01:02:05)
Continuity mistake: On Sidney's porch, Tatum tells her that maybe her mother was having in fact an affair; in that wide angle her left pigtail is behind her shoulder, but in the close-up it is in front. (00:53:30)
Continuity mistake: The costume of Ghostface/Father Death is stuffed inside the plastic bag in two different ways in the shots when Sheriff Burke is checking it out - look at the bits coming out in the close-up. (00:35:05)
Continuity mistake: Billy holds Sidney in his arms after the attempt at her life downstairs. She clings to him and pulls at his jacket, that is unperturbed in the close-ups on Skeet Ulrich. (00:29:55)
Continuity mistake: When Sidney manages to kick Ghostface away after he has almost stabbed her behind the front door of her house, she sets up the kick shouting "no" and shielding herself with her left arm, but in the shot of the actual kick the stuntwoman's left arm is on the ground. (00:28:55)
Continuity mistake: In class, the teacher tells Sidney "It appears to be your turn." One of her classmates, a girl with a grunge shirt, turns around to look at her, but in the next shot she's looking ahead. (00:18:55)
Answer: Characters in horror movies are notorious for not doing the most obvious things. It's most likely that she was scared and not thinking straight at receiving numerous threatening phone calls, particularly when she is threatened after hanging up on the killer.
Manky
Also, when she told the caller that she was "two seconds away from calling the police", his response was that they'd never make it in time. She also knew he was nearby as he made comments that indicated he could see her. She didn't know it was someone that knew her. She's a teenager and scared, so her judgement was clouded. She reached a point where she believed her only chance was to get away from him by either fighting him or getting out and hiding somewhere outside.
dewinela