Deliberate mistake: In the final battle at the end, Mark Loftmore enters the back room where we see Mr. Lincoln leaning over the body of an older man with a red jacket whom Lincoln has apparently just shot. This same man later appears in the background of at least one shot of the general melee taking place outside in the gallery.
Plot hole: When James and Gemma arrive back at the waxwork just before the film's climax, they claim a "man with a high-pitched voice" (Hans) invited them. In the earlier scene when they decided to not enter the waxwork, they left before Hans answered the door, and he couldn't have found their phone numbers anyway.
Continuity mistake: In the vampire sequence, there is a long shot at the dining table where the Count makes introductions. The Count is standing and China begins to sit down with a butler helping to push in her chair. Then we get get a medium shot of the Count rising from his chair. Back to the long shot where China sits down again, this time without help from the butler.