Revealing mistake: When Jesse is cleaning out his room, he puts a tape into his tape player, and presses a button down on the top of it. But halfway though the scene of him packing his things away, you can clearly see the button is no longer pressed down, yet the tape still plays.
Plot hole: When Freddy takes over Jesse's body at the party, there are several people watching through the patio doors when he confronts Lisa. None of these people ever make a sound, even when they see Lisa have a knife fight with a horribly disfigured man with long knives coming out of his fingers. The other party goers are completely oblivious to Freddy's presence until he comes jumping through the glass doors.
Continuity mistake: When Jesse and Lisa first arrive at the boiler room factory, Jesse says to Lisa "How long has it been closed down?" And then Lisa replies. To the left of them you can see a large machine, which Jesse and Lisa are standing well away from. But as the shot changes, they are now standing right beside the machine.
Audio problem: When Jesse and Ron are doing press-ups on the sports field, Ron says "So what about you and that rich babe you've been cruising to school with every day?" You can see that Ron starts to move his mouth a few seconds after the words are spoken, and his mouth doesn't move correctly to the words being spoken either.
Continuity mistake: At breakfast, when Jesse's sister goes to sit where Jesse is about to sit, Jesse says "No!" to her and she sits back in her chair, still trying to get the plastic claws out of the cereal box. As she tries to get the claws out, she is holding the top of the cereal box with her left hand. Then in the next closeup of her, her hand is down by her side.
Continuity mistake: When Jesse and Lisa are reading Nancy's diary, Lisa reads the first entry and it says all about Nancy dreaming of Freddy. The next entry that Lisa reads is about Tina being killed.If you remember in the first Nightmare, Nancy does not find out Freddy's name until after Tina is dead. The entries in the diary are not in order.