Plot hole: When Jason is in Ginny's cabin, she's under the bed seeing where he's at. So how did Jason manage to get up on a chair and wait for her to come out without her seeing him do this? She had to see him do that, but when she pokes her head out, she's surprised to see him there.
Suggested correction: She was a bit preoccupied with the rat that got up close and personal to her. She heard the creaking, but when she looked back, she didn't see him, assuming that the sound was made by him exiting through the cabin's door. The creaking was actually him getting up on that chair, but she wasn't looking at the door because the rat was in her face.
Plot hole: Jason drags Vicky's body down the stairs. A minute later, Ginny and Paul come in the house and see nothing. Jason even has time to hide Sandra and Jeff's bodies by the time Ginny and Paul go upstairs. Not possible in a two minute time frame.
Suggested correction: We're not given a specified length of time between Vicki's murder and the time Paul and Ginny returned. He could have had enough time to hide Jeff and Sandra, but then they arrived as he was dragging Vicki down the stairs (you could hear them outside as we see this). We didn't see every closet or room, so the bodies could have been hidden anywhere.
Revealing mistake: When Jason is on top of Ginny's car, she reacts to the pitchfork through the roof a second too early. (01:10:50)
Suggested correction: She had just seen Jason through the window before he disappeared. Then the pitchfork comes the roof. Just before she screams, you can hear the pitchfork tearing through the fabric of the roof. That's what's she's reacting to.
Also, when you see the car and Jason is reaching in through the hole in the roof from the passenger side, it's pretty obvious she would have seen him before he stuck the pitchfork through. That could be another reason she react before we see the pitchfork.
Other mistake: Vicki enters the darkened cabin and flips a switch on a nearby lamp, to discover the power is out. But as she grumbles and crosses to another table lamp that is unplugged, she plugs it in, and suddenly the whole cabin lights up.
Plot hole: While underwater all of those years, Jason didn't seem to age. He seemed to be a child when he grabbed Alice at the end of the first film. How could he grow up to be an adult after only five years, as Paul stated during the campfire story?
Suggested correction: Dialogue in the film hints at what actually happened, which is that the end of the first movie was some sort-of panicked dream/delusion Alice had, while the real Jason has been living out in the woods ever since he "drowned," and thus aged into an adult. (Whether he actually did drown and came back to life, or escaped and fled out into the woods because he was mentally challenged is up for debate.) It's admittedly shaky, but the movie does hint at an explanation, so I don't think this really counts as a mistake.
