Ace fights a pair of Haemovores on the roof of the church, during which the mask of one of the actors becomes dislodged from the neck of his costume. The Haemovores also drop out of character during the fight, emitting very human sounds of grunting as they are attacked (in contrast to the inhuman, post-production sounds of pain they otherwise make in this serial).
When the Haemovores bust open the "iron shutters" at the mineshaft entrance, one of the doors wobbles as it's flung open and on the other a panel comes off in a rather rubbery fashion.
The Doctor says that Dracula was based locally. Dracula is based in Whitby, which is in North Yorkshire - this story is set in Northumberland.