Other mistake: In the scene at the beginning where Phil eats Jason's Heart, you'll notice that he screams like a monster for a bit. Don't you think that the two security guards would easily hear the screaming and intervene, being that they're in the very next room? (00:13:40)
Other mistake: When Robert, who is possessed by Jason, is reaching through the car window to get Jessica and Steven, you can see his reflection on the car hood. This reflection should show Jason, as we've already seen in the movie that the host body Jason is in should show Jason in any reflection. (01:00:50)
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.