The film was shot without sound and the dialog was dubbed in after principle photography. Reportedly while directing the cast on the set Bava would play Rodrigo's "Concerto d'Aranjuez" to get the emotion he desired from the actors.
Sophia Lehar: I prefer ghosts to vampires, though. They're so much more human; they have a tradition to live up to. Somehow they manage to keep all the horror in without spilling any blood.