Continuity mistake: At the diner where the Jason Burgers are being sold, Ward complains about not being able to make the patties correctly, so Joey demonstrates. As she makes the two eyeholes with her finger, the patty changes places on the counter between shots. (00:20:20)
Continuity mistake: When the Coroner is stopped by the two security guards, he places his pizza box a bag of drinks down on the table. One guard then pats him down and then in the next shot the position of the drinks bag on top of the pizza box has changed. (00:14:40)
Visible crew/equipment: When Jason runs onto the large shooting field, swat members start shooting him. In one shot behind Jason, you can see a black hose running across the grass, and going up into the trouser of his right leg. (00:06:25)
Continuity mistake: When the light bulb explodes, Agent Marcus takes the old, burnt bulb away, and puts it on top of the metal ladder she's standing on. In the next shot she descends the ladder and folds it up, with the old, burnt light bulb having mysteriously disappeared. (00:02:50)
Revealing mistake: As Agent Marcus runs through the woods, away from Jason, all she wears is a white towel around her body, which is just tucked in and over at the top. However it is very obvious that the towel is clipped together round the waist, in order for it not to fall of, most obvious because she trips, climbs over branches, etc. and the towel is always tightly secured. (00:05:15)
Other mistake: When Jessica first goes to her mother's house after her murder, her friend asks why she didn't tell her about the baby. Jessica says she was going to tell everyone but didn't expect to be back so soon. She just told her mom on the phone she was going to visit the following weekend so yes she did.
Continuity mistake: When Steven fights the possessed sheriff at Diana's house, they hit the table knocking the lamp on the floor. You hear it shatter yet it's still lit.
Visible crew/equipment: When Jessica enters the living room, and Vicki is cleaning the bloodstain, you can see a boom mike pole in the top right corner by the ceiling fan. (00:41:35)
Continuity mistake: When the coroner sees Jason's heart beating, from shot to shot he has a little blood, then a lot, and then just a little again, but when he goes to actually eat the heart there is a lot of blood smeared on his cheek and face. (00:12:30)
Continuity mistake: The pole that impales Deborah moves from going though her chest just below her boobs, to much lower down, in her waist between shots. (00:31:55)
Revealing mistake: After Vicki has been killed, Jessica mourns by her body. She then proceeds to stroke Vicki's hair and face. Well, Vicki dies with her eyes wide open. However, as Jessica strokes her face, Vicki closes her eyes. Her eyes then remain closed for all the following shots of her. (01:10:20)
Continuity mistake: When Josh transfers the Voorhees creature into Robert's mouth, blood runs down Robert's right cheek as this transfer is made. Once Robert then wakes up as Jason, the bloodline has swapped cheeks. (00:56:40 - 00:58:00)
Continuity mistake: When Randy drives out to pick up Steven, Randy takes off his police hat and puts it on the hood of the car. Randy then punches Steven, and in the next shot you can see the police cap has vanished from the hood. Cut back and it's there again. (01:03:15)
Answer: Of course he would be reborn exactly like he was before he was blown apart. Which is why he needed a blood relative to do so.