Visible crew/equipment: Near the end of the chainsaw sequence, a crewmember's hand is visible on Krug's back.
Other mistake: Near the end, as Van Helsing parts the wooden fence and enters St Botulph's churchyard, the camera tilts up and catches two builders on top of a construction sight watching the filming.
Factual error: The colt .45 that Telly Savalas uses didn't come into use until 1911 (the film's set in 1909).
Continuity mistake: While Prince Mamuwalde struggles with Count Dracula's goons, some candles are knocked off a candelabra, but the next shot shows the candelabra with the full complement of candles it had before the fight.
Continuity mistake: Pickett Smith has his shirt sleeves rolled up at the movie's beginning, then they're rolled down and buttoned then rolled back up before his canoe gets knocked over.
Other mistake: When the wrapped body parts are going for the mistress (the one telling the story), you can see the right arm dragging itself across the floor. However, the arm that grabs her face from above is also a right hand. How did the murdered wife have two right arms?
Continuity mistake: When Louise is in the study, sunlight is coming through the manor house windows, even though it's supposed to be nighttime.