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.
Sir James Forbes: I, I find all kinds of witchcraft slightly nauseating and this I find absolutely disgusting.