Factual error: At the end, during the master wide shot of Diana and Shandor (C19 characters) standing over the castle moat, there is a modern aeroplane's vapour trail high above their heads.
Factual error: Although set in 1860, virtually all the costumes/clothing in the film are far more typical of the later Victorian period. For example, the police are wearing cork helmets, tunics, and Duty Armlets with upright stripes. These items were not introduced into the Metropolitan Police until 1863, 1864, and 1886 respectively (and this would have been delayed further in a small backwater Cornish town). In 1860, they would be wearing top hats, swallow-tail coats, and Duty Armlets with horizontal stripes.