Continuity mistake: The footage of Dracula impaled on a giant golden crucifix at the end of 'Dracula Has Risen From The Grave' is re-cut for the pre-credit sequence of this film. However, when the second film continues, the golden crucifix is missing in the background, behind Dracula's powdered blood and collapsing cloak, creating a continuity error with perhaps an unusual reason for happening. Hammer props department may have rid themselves of the crucifix between films shot a year apart.
Revealing mistake: When Paul is carrying the dead body of Lucy from the lake her arm comes up to stop herself from falling.
Factual error: The lock on Secker's front door, seen in the shot when he returns home from Highgate Cemetery, is a modern (stainless steel) Yale lock and barrel, not a High Victorian dead lock; his front gate is made of paper-thin iron from the 1960's; the lamp post Screen Left is supposedly gas-powered but has an electric feed running over the pavement.