Other mistake: After the Joker has become a vampire, you can still see his reflection in metal poles and such while he is chasing Batman in the bloodbank. (00:47:00 - 00:49:00)
Factual error: Loosely based on the novel by Jules Verne, the entire story takes place on a remote Pacific island in the early 1860s. However, as pirates come under attack by a sea monster (in the second half of this two-part film), a modern fishing trawler or tugboat appears momentarily on the far right of the screen. (00:59:05)
Continuity mistake: During the chase after John witnesses a woman get kidnapped, one of the thugs shoots out of the driver's side headlight of his blue van. A couple of shots later, the headlight is back in and it's there for the rest of the chase.