Continuity mistake: When Reggie finds the bodies in Tommy's room, Violet is first propped against the wall, but in the next shot, she is lying down, then she is propped up again. (01:09:00)
Continuity mistake: As Reggie rides the tractor towards Jason, his hood keeps changing position, probably in order to cover up the stunt driver's face. (01:11:10)
Continuity mistake: When Reggie discovers the bodies, blood appears on Violet's face in between shots. (01:09:00 - 01:09:05)
Continuity mistake: When Lana carries the cat to the door, she is holding it in her right arm while she reaches out for the light switch with her left hand. When it cuts, from the outside view she holds the cat in her left hand, while reaching with her right hand. (00:36:00)
Continuity mistake: We see Vic outside the halfway house, just starting to chop a 4-foot log with a double-bit axe. In the same scene a few moments later, as Joey approaches, Vic has chopped about a third of the way through the log. Problem is, it's a completely different log (different shape, texture and color).
Continuity mistake: After Reggie's grandfather flies through the window, his head changes positions between shots. We can also see that he is breathing, even though he is dead. (01:10:10)
Continuity mistake: When Robin and Violet hang up the laundry, the distance between the pink towel and boxer shorts increases between shots. (00:18:15)
Continuity mistake: At the beginning of the film, we see boots walking through the woods. In a closeup they stop, and to the left boot there's a cluster of leafless branches. In the following shot from behind, they are gone. (00:00:50)
Continuity mistake: In the film Joey has chocolate on his face/left side of his mouth. The amount of chocolate changes on his left side as he is walking off the porch towards Violet. (00:18:00)
Continuity mistake: In the film Tommy tosses the alien mask that he wore to scare Reggie on his bed and the mask slides down the wall and is all crinkled up. In the following shots Tommy takes out another mask and you can see the alien mask now laying flat on his bed and away from the wall. (00:13:10)
Continuity mistake: In the film the killer.aka."not the real Jason" is seen walking through the rain soaked grounds and woods , but yet when he climbs up the ladder at the end of the film his shoes are pretty clean. (01:10:30)
Continuity mistake: When young Tommy is looking at Jason's grave the amount of leaves on the grave change between the shots. (00:01:20)
Continuity mistake: Jason stabs the machete vertically into the man's stomach, but when he pulls it out the machete is in horizontally. (00:03:30)
Continuity mistake: After watching "A Place in the Sun," Robin goes to her room and removes her blue gown. Then she walks to her mirror, and in the reflection we see the white door at the end of her bed is wide open. In the following shot into her mirror, the door is shut. (01:02:20)
Continuity mistake: The handle of the machete Jason stabs both grave digger guys with changes between shots. As he stabs the 1st guy, the handle is tripoint, but as he stabs the 2nd guy through the neck then pulls back, the handle now has a rounded end like a wooden peg.
Continuity mistake: As Tommy reaches Jason's grave, he hears laughter and voices coming from the woods. As the voices move closer we see lights in the clearing. Tommy runs off in the bushes to hide. Moments later, two guys with flashlights and shovels suddenly rush in, from the opposite left, instead of the clearing path at the right, from where they were.
Continuity mistake: While Eddie is being killed, in the second shot, there's a blood driblet on his bottom lip. In the next shot, his bottom lip is clean without any blood residue.
Continuity mistake: When Lana is hit by the axe, it hits her horizontally, but in the shot of her corpse, it is shown vertically.
Continuity mistake: After Pam runs out of the house towards the barn, she sees Roy coming, and then she trips, as she crawls her shirt sleeves are rolled up, but they weren't before she tripped.
Continuity mistake: In the film Demon is in the outhouse and is sitting on the bowl when it begins to shake. The toilet paper changes amounts on the roll between shots. (00:53:00)
Answer: He simply just snapped. He definitely looked angry before Joey even started talking to him, and said how he hated being there...and he already had an axe in his hands...he just lost it, and took out his anger and frustration on Joey.