Revealing mistake: Look closely at the footage when the vampires are entering the cave. Later when they are exiting the cave, the waves are flowing backwards. The same footage has been reversed. (01:17:05)
Continuity mistake: Near the middle of the film we see that Michael has a transparent reflection in a mirror because he is a half vampire. Yet, earlier in the film when the other vampires, who are full vampires, are in the video store, their reflections can be clearly seen in a glass counter. (00:12:10)
Continuity mistake: In the scene at the beginning of the movie where the flying vampires are chasing the security guard across the boardwalk parking lot, the positions of his arms as he is running changes back and forth between shots. In the close-ups of the guard's face, his hands are up, holding his hat down on his head. In the wide shots, his arms are down at his side. (00:02:45)
Continuity mistake: The family dog bites Michael on the left hand in order to "protect" Sam, which leaves a nasty, bloody gash. As Michael runs up the stairs to talk to Sam, he leans the palm of his left hand on the railing a couple of times for balance. There are no bloody hand marks when he picks his hand up. (00:40:00 - 00:40:45)
Continuity mistake: When the mother is leaving a bottle of wine at Max's house and is being chased by the dog, the dog lunges through the fence. The fence slightly breaks apart by the dog's mouth. The shot changes, and the fence is intact. Another shot and the fences has an even bigger gash in the side, and again, intact.
Continuity mistake: During the opening we see Michael, Sam and their Mom enter the town and check it out. Michael asks a man if there are any jobs in town. The next time we see Michael he's taking his motorbike off the trailer. Then we see him in the car for one shot. When they reach Grampa's house he is riding the bike. (00:04:55 - 00:06:05)
Continuity mistake: When Sam is taking a bath, at one point the bottle of shampoo is there and then missing when Michael enters the room. Then when Sam pops up from under the water, after Nanook attacks Michael, he grabs a blue towel to wipe his face. There was no blue towel previously in the scene, only a yellow one. (00:38:35 - 00:58:45)