Continuity mistake: When Ginny is in the VW, she knocks Jason over with the car door. After, Jason gets up twice. (01:08:15)
Continuity mistake: When Jason enters Ginny's cabin, all that is shown are his feet. After running through rain and mud, he leaves no tracks whatsoever, and his shoes are spotless. (01:10:20)
Continuity mistake: As Ginny hits Jason in the shoulder with the machete, in the first shot it catches part of his sack and is embedded diagonally. In the next shot, the blade is clear of the sack and the machete is now perfectly horizontal. (01:16:55)
Continuity mistake: The photo pinned beside the window changes in appearance and position during shots. (01:18:45)
Continuity mistake: When Jason comes smashing through the window at the end, to attack Ginny who is getting up from the cot, the camera angles are inconsistent with the attack. First he is lounging at her from behind, to grab her. Then his distorted face is suddenly at her left shoulder before he's even touched her Then she's looking back at him and screaming before his hands even touch her and pull her out of the window. (01:24:20)
Continuity mistake: When Scott gets his throat cut, blood pours out. Yet when Terri spins him around, there's no blood anywhere on him except a small amount on his shirt sleeves.
Continuity mistake: When Sandra and Jeff sneak off to Camp Blood they walk right along the waterline with the lake on their left, yet after crossing the barbed-wire fence, the lake (in the background) is on their right; this was a mirrored image.
Continuity mistake: Jason drags Vicky down the steps all bloody, yet doesn't leave any blood on the steps.
Answer: Probably from inside the building he was standing in front of.
lartaker1975