Revealing mistake: One of the burning zombies at the very end of the film is wearing the most terrible and obvious fire-proof mask and hair-piece, made all the more noticeable by being used so prominently in front of the camera several times.
Continuity mistake: The Squire's main henchman, Denver, ends up being pushed into a fire before being stabbed to death by Sir James. When Denver is first shown falling into the fire, he goes down face-first, with his left arm catching fire. The shot changes, and then suddenly he is face-up, and it is his right arm that is on fire.
Revealing mistake: When Sir James breaks into the house of Squire Hamilton, we are shown a long shot of the tin mine underground with the zombies being whipped by the Squire's men. Watch the back of the shot - several blows from one man hit a couple of the wooden props supposedly supporting the roof, which obviously wobble about and show they are just for decoration rather than any practical purpose.
Continuity mistake: Squire Hamilton and his men make an unsuccessful attempt to retrieve the zombified Alice. When Sir James and Dr Tompson return to her lying in the now open grave, a longer shot shows her already wearing her grey zombie makeup. When it changes to the close-up of her face, she appears normal again but is then shown changing into her grey zombie appearance before rising from the grave in an obvious continuation of the original longer shot of her in the open grave.
Revealing mistake: The zombie of John Martinus throws the lifeless body of Alice from the tin mine pit head onto the ground. When Sylvia examines the body after, Alice very obviously blinks. Visible at normal speed, but easier to see slowed down.
Continuity mistake: When Squire Hamilton causes Sylvia to cut her hand on broken glass, the amount she is shown to bleed is realistically very small. When he transfers it almost immediately into another glass container, it is suddenly and unrealistically a much larger amount.
Other mistake: When Sir James examines a book on witchcraft in the Vicar's library, it is a photographic reprint (more contemporary to 1966) of a much older, original book.
Continuity mistake: As Alice discusses Squire Hamilton at the Tompson house, we see Sylvia putting away some of her clothes into a wardrobe. She puts a large dress onto a hanger, and inside, which immediately disappears when the shot changes. She then puts another smaller item onto a hanger and inside, and when the shot changes, she can be seen putting the same item into the wardrobe again.
Continuity mistake: When Sir James and Sylvia arrive by coach at the Tompson home, the driver carries their baggage to the door. He is played by a younger actor with darker hair initially, but when the shot changes to the door of the house, he is suddenly being played by a noticeably older actor with grey hair yet wearing the same clothes and still carrying the same bags.
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.
