Continuity mistake: In the shot of the alien's tail wrapping around the back of Lambert's legs right before it kills her, the floor is different to what it was before, there is water suddenly falling from the ceiling when there wasn't before and her trousers have changed from white to blue. This is because that shot was originally intended to be used when Brett was killed.
Continuity mistake: In the beginning, when Mike and Jody raise the hood on the car, Jody's hand holding on to the hood alternates between his right and left hand over three shots. (00:13:10)
Continuity mistake: When the stairs are first shown, there's carpet up the middle of the stairs. At the end when they flee the house it's gone.
Continuity mistake: When Watson is conned by the prostitute who says she knows Mary Kelly, she lures him into a closed alley. After Watson has called the police and subdued the attacker, 2 constables arrive and arrest Watson, but as they all leave, a third constable comes from behind the camera. Either he magically appeared, or he walked through the wall behind.
Continuity mistake: When Ryerston is dead already and is talking with Matt, the autopsy scar next to his neck keeps changing sides.
Continuity mistake: During the underwater scene where the zombie is fighting with the shark, the zombie's arm is bitten off by the shark. However, we see him with the arm after he loses it, and without the arm before it is bitten off.
Continuity mistake: Van Helsing and Seward discover Mina's grave empty, and go underground to look for her. Van Helsing finds her first, to discover she is now the undead. As Mina advances, Seward enters, pulls her off, and they struggle as Van Helsing grabs a stake. Mina is then "thrown" back into Van Helsing's arms, and gets impaled. As the camera pulls away, Mina lays lifeless in Van Helsing's arms as he weeps. The stake, however, has disappeared. Where'd it go? It should be sticking clear out her back, covered in blood.
Continuity mistake: When Jonathan returns to his town and don't recognize his wife, his coat disappears in the next shot when he ask to the man beside him who she is. He didn't have the time to remove it. (01:14:15)
Continuity mistake: The babysitter answers one of the early calls saying "Robert, I don't think this is very funny." The pencil and papers have completely changed position on the table. (00:07:30)