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.
Deliberate mistake: We see the Air Force plane's bomb bay doors come open. But in the next shot of the plane banking, the doors are instantly closed again. (00:45:20)