Other mistake: In the final scene of the movie, Megan starts a boat motor and uses the propeller to hit Jason in the face, who has been chained down underwater. But if Jason can only barely reach her foor from underwater, there's no way the boat propeller is underwater far enough to reach his face.
Trivia: Director Tom McLoughlin revealed in a 2017 interview that he was approached at one point to write and direct the seventh installment of the series after "Jason Lives" proved popular. Knowing the studio wanted to make "Freddy VS Jason" at that point but couldn't due to legal rights, McLoughlin pitched another crossover idea - "Cheech and Chong Meet Jason", a farcical comedy starring the stoner comedy-duo in the vein of the old Universal "Abbot and Costello Meet..." films. The producer thought the film would do well with comedy audiences and was entertained by the idea, but ultimately decided it would alienate horror fans too much and it never moved forward.