Deliberate mistake: Robert Brown wears a gold turtleneck sweater with his leather outfit throughout the series. Though it's more than 100 years beyond the show's 19th Century setting, he and the producers decided that he looked good in it, so allowed the anachronism to stand.
Revealing mistake: The mock-up of Clancey's ship that we see from the town never matches the stock footage of the ship at sea. Nor, apparently, did budget restraints allow for any movement of the mock-up that would make it appear to actually be floating on water. It glides into port on what is obviously wheels, perfectly level, and without a single creak or groan that a real ship would make.
