Plot hole: During the first fight scene between Freddy and Jason in the dream world, Jason tosses Freddy into some pipes which causes water to spray everywhere. When Jason is about to attack Freddy and stops to back away from the water, it is explained that Jason is "afraid" of the water. While logical on paper, this makes absolutely no sense with the rest of the Friday the 13th movies and an earlier scene in Freddy vs. Jason. Jason has on many occasions ventured freely into Crystal Lake to kill his victims in earlier movies, and in this movie he walks all the way to Elm Street in the pouring rain. Surely if he was afraid of water he'd not have completely submerged himself in a lake, and would have taken shelter under a tree until the rain storm passed.
Revealing mistake: When the drug "Hypnocil" is researched on the Internet, an article about the drug appears. If you pause the shot and read the article, you can see that it has nothing to do about Hypnocil. The article is about drug testing of students who engage in extracurricular activities. (00:55:10)
Revealing mistake: As soon as the drunk kid sets Jason on fire there's a few quick shots of Jason's face but there's a perfect hole right through his head where his eye is supposed to be and you can see the night sky through it. Some people say it's a reflection off the goggles to protect the actor from the flames. Either way it's a mistake. (00:40:45)ang_hulk
Continuity mistake: When the girls are at Lori's, just after Kia asks them if they think she needs a nose job, the lights flicker. When they flicker Kia is holding a compact in her left hand and she begins to close it. Both hands are up by her face but then the angle changes to a wider shot and her left hand is empty and on her lap and the compact is in her right hand as she places it on the sofa.Hamster