In part 9, Jason's head was all bubble like, with no hair. In this film his head looks normal, with hair. Timeline-wise Freddy Vs. Jason was before this film so it should have explained the loss of the bubble head.
Kat's Explanation: Jason was in "Hell" and brought back, by Freddy. We know from the beginning of this movie and Freddy Vs. Jason that he is able to regenerate.
In Pt 7, Jason's left eye was rotted out, in Part 8, it was his right eye that was rotted out, now he's got his right eye, and doesn't appear to have a left one. Adrienne took it out, but there didn't seem to be a hole there.
He lost his axed marked mask at the end of Part 7, but got another one like it in the beginning of Part 8, which was later lost again. Its unknown where he got his mask in Part 9, but he did lose it in the dirt, so how does he now have a mask with that same axe mark?
The guy on the computer screen that the Professor is talking to says that Jason has killed nearly 200 people. We aren't sure how many people were on the Boat in Pt. 9, but its not close to 200.
Kat's Explanation: Remember the timeline, there is still room for more films before this one. At the time of filming the information would be incorrect.
Rowan was frozen in at least 2010, since the freezing unit was built in 2010. Kay Em says that Rowan has been out for 4.55 centuries, and the year is now 2455. Which means that Kay Em was wrong. Rowan has only been out for 4.45 centuries.
Kat's Explanation: Its only assumed that she was frozen in 2010 the date couldn't be any later then that if the model of the machine Jason was frozen in was built in 2010.
Dealing with the same type of error. The professor first says that Rowan has been out for 455 years. That would mean she was frozen in 2000, but contradicts what Rowan says later when she is talking about how they tried to execute Jason in 2008. A few minutes after the professor says this, he then says she's been out for 450years.
In the beginning, before Jason is frozen, he gets a machete all of the sudden. Where does he get his machete from? He had been locked up in that room for what looks to have been at least a little while, you'd assume they wouldn't want to keep a killer locked in a room with his weapon lying around.
Rowan was sitting up when she was frozen. When the group of students find her she is lying down on the ground hidden under a bunch of tubes.
Kat's Explanation: Its been so many years that she has been down there, that it is possible there were many storms or earthquakes which knocked her over.
Another error in the same scene. Rowan gets frozen with her eyes open, but when they find her, her eyes are closed.
Kat's Explanation: Maybe we didn't see her whole freezing process and she eventually closed her eyes
Adrienne went in through Jason's left eye socket, but when she lifts up his mask there doesn't seem to be any opening there.
If Jason's body was thawed out enough so his blood was leaking out, he could move, and he was wet from where the other ice had melted. Shouldn't the small amount of ice on his hands be melted as well?
The mark where Adrienne cut into Jason's skull was right around the edge of his mask, but later when he is walking around killing everyone, the mark is a few inches away from the mask.
The freezer tank that Jason is in is very thick and strong, you can tell just by the way Rowan closes the door, and you can see the thickness of the door. So how in the world did Jason's machete slice through the door, and then into Rowan?
In the scene where Adrienne dies, he dunks her head into the liquid nitrogen. How does Jason know the scientific properties of liquid nitrogen?
Kat's Explanation: He can't. He probably thought he'd drown her, and then realized her face froze.
At the very end, there is a couple looking into the sky. The girl says "I think it landed in the lake" but she's obviously still looking at the sky, not towards ground level.
How does the professor know Jason's name to label him as "Jason Voorhees"? He gives him a name before he speaks to Rowan, or to the man on the computer. As the man on the computer states "The other viable is marked Jason Voorhees"
Rowan is wearing earrings when she is frozen, but not wearing them when she is on the repairing table.
Kat's Explanation: They probably took them off of her so nothing weird would happen.
When Adrienne has a close up where she is supposed to be looking at Jason's eye, you can tell she isn't really looking at it, but almost as if she's looking higher up and beyond.
When Jason punches a hole through the ship, everyone starts flying around. They even start shouting. If everything was being sucked out of the room, do you really think they'd be able to breathe, or even talk?!?
Since when can Jason's lost and damaged tissue regenerate?
Kat's Explanation: I suppose he could have always been like this but there was never anyone around to check him out so we never knew.
In the beginning there is a man who is thrown out the door, and Rowan starts talking to him. How did that guy die? He only had a little blood on him, and there didn't seem to be any wounds.
In the scene in the beginning when one of the men are thrown through the door, and Rowan talks to him, he dies, then all of the sudden Jason is behind her. How is that possible if there was no other door out of that room other then the one that Rowan was in front of?
Kat's Explanation: We don't know for a fact there wasn't another door.