Dracula Prince of Darkness (1966)

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.

Alan Kent: You forget about all of this in the morning, you'll see.
Helen Kent: There'll be no morning for us.

Trivia: In an interesting possible predictor of the future, the British husband and wife heroes of this British film are named Charles and Diana.