Visible crew/equipment: When Sarah pulls the severed arm of the killer, behind the debris, you can see in the shadows a crewmember who was holding it from the other side and then let it go at the right time. (01:29:40)
Continuity mistake: Axel and the girls are making their way through the mines. He stops and tells them to hush. In the first shot, you can see Sarah is holding her friend with her hand under the girl's hair. Switch to a closer cut, and Sarah's hand is over Patty's hair. (01:13:10)
Continuity mistake: When Howard and the girls find, or rather, are found by the corpse, Patty reacts with horror in close-up, putting her hands in front of her mouth. In the next shot, her hands are on her knees, and only then does she bring them to her mouth. (01:10:20)
Continuity mistake: When Hollis is shot with the nail gun, he has a bloodstain on the lens of his glasses in one shot, and the same lens is clean a moment later. (01:09:35)
Continuity mistake: Howard has to get down from the shaft after scaring Hollis and the girls. His lantern is in his right hand, left hand at the cut. (01:04:05)
Continuity mistake: In a baffling decision, the 6 main characters decide to have a little tour of the mines at night on Valentine's Day. They exit the building. T.J. goes after them and slams the door shut, which is open behind him in the next shot. (00:55:50)
Continuity mistake: After the police chief turned his car around, we see Sarah asking the boys to have a trip down in the mines. Howard listens, rubbing his own cheeks with his fingers in one shot, and is in an entirely different position in the next. (00:55:00)
Continuity mistake: When Axel storms out of the party because of the altercation with T.J, the door lost the paper heart decoration it had in previous scenes. However, when Little John gets back to the party room, the heart is still there. (00:47:40 - 00:50:35)
Revealing mistake: Axel beats T.J. up at the party before Hollis breaks them up. Still fired up, he grabs a can of beer, opens it and goes through the door. When he walks outside, he holds the can heavily tilted, almost horizontal at one point - if it were a freshly opened real can, it would have spilled beer all over him. (00:47:40)
Continuity mistake: At the party, Axel wants to show off kissing Sarah, but she stops him. During the scene, her hair and her hand position against Axel's jacket change between shots. (00:46:30)
Continuity mistake: When Chief Newby reads the message accusing him of not stopping the party, the envelope is visible or not visible depending on the shot. (00:45:40)
Continuity mistake: In the scene with the dogs outside the police station, depending on the camera angle, the dogs eating the bloody package are the two yellow ones or the black and white and one of the yellow ones, the other just circling around. (00:45:00)
Continuity mistake: When Sarah and Axel get to the party after T.J., Axel puts his hand on the door in a different spot between shots. (00:42:25)
Continuity mistake: When Newby opens the Valentine box delivered to the station, he holds the card in a different way between shots (the close-up is more camera-friendly, picking both ends by the sides to offer a perfect view). (00:41:55)
Continuity mistake: During Happy's killing, the Miner's mask is without the left lens for just one shot. (00:39:40)
Continuity mistake: As Happy sets up the prank in the mine office, he goes back to check his masterpiece one time too many. Notice as he turns that there are loose locks of hair on his forehead that weren't there before, and they vanish when he opens the door for the last time. (00:39:20)
Continuity mistake: When Newby meets Sarah for the obligatory jumpscare, he is pointing the longest flashlight in the world at her face. He turns it off and lowers it. Then in a single shot, he still has it pointed at her face, and then it's low again. (00:35:40)
Continuity mistake: In the romantic scene where T.J. takes Sarah to 'that spot', her hair keeps changing position between cuts, the wind suddenly becoming still from one take to the next. (00:32:00)
Continuity mistake: When T.J. manages to get Sarah into his car for a romantic interlude, there is a single shot (when she says "T.J., will you stop this" without ever meaning it) where the rear view mirror on their side is askew (probably one of them accidentally leant on it), but it's totally straight in the other shots. (00:31:50)
Continuity mistake: Sarah is talking to her friend about the two guys who are after her. During the walk, Patty's bag is dangling off her elbow. But the moment they stop and the angle changes, she is wearing her bag with the strap on her shoulder. (00:25:15)
