Corrected entry: Producers Brad Fuller and Andrew Form were keen to show the actual definitive origin of Jason Voorhees' hockey mask which was always a slight mystery in the original series. Quoting from an interview; "Yes, you definitely see where the hockey mask comes from and why he puts it on and all that. It's like Part II to Part III for us - Part II is the sack and Part III is the mask - and we took them both. It is a story point and hopefully we've shot it properly in a way that when he takes off the sack and puts on the mask, he is now the Jason that everyone knows and loves."
Corrected entry: In the trailer, the lady water boarding half naked falls into the water by tipping over, but in the movie itself, she hits a wave and flies in the air and into the water.
Correction: Differences between trailers and the finished product are not valid movie mistakes.
Corrected entry: If Jason didn't intend to kill Whitney, why did he run up to her and swing his machete right down on her to the point where he wouldn't be able to stop? It's just to trick the audience, but makes no sense in the actual movie.
Correction: Jason probably didn't see the resemblance between Whitney and his mother (which is why he doesn't kill her) until he got close to her. Also, despite the speed of his chop, he still would have been able to stop it in time.
Corrected entry: When Chewie has the shot of alcohol with the flames on the top of it, the actual flame disappears in one shot and the height of the flame differs a few times as well.
Correction: Having consumed many flaming shots myself, I can attest to the fact that the flame height and visibility can vary. In fact, I have burned myself on a shotglass because I did not know it was even lit.
Corrected entry: Jason has kept Whitney hostage for six whole weeks, yet her condition, appearance and physical strengths seem to be unrealistic for the given scenario.
Correction: Jason very obviously fed her as well as himself. Whitney wasn't kept in a mud pit, but on a bed. I do not see how her state in the movie is contradictory to the plot.
Correction: What mystery? In the third film of the original series, a guy scared a girl wearing a hockey mask. Then he wandered into a barn where Jason was hiding, still carrying the mask. Jason then killed the guy and took the mask, and the rest is history.