Christopher Lee found the lines given to this character so awful that he chose to play it silent.
Filmed back-to-back with Rasputin: The Mad Monk (1966), using many of the same cast members and sets.
According to the DVD commentary by Barbara Shelley and Susan Farmer, all of Barbara Shelley's screams were dubbed over by Susan Farmer.
Originally shown (in London) in a double billing with The Plaque of the Zombies (1966).
In the scene where Dracula finally wakes up (his "resurrection" in his coffin), to the crash of thunder and a flash of lightning, he originally took, as probably anyone would, a full FOUR frames (one sixth of a second) to completely open his eyes. In the final cutting stages, an assistant editor had the idea of removing those four frames -- effectively a "jump cut" -- to have Dracula's eyes open in an even more shocking ONE frame. However, the editor, Chris Barnes, had already finalised the edit for that reel -- so the clever cut was never incorporated!
In the scene where Dracula is being "resurrected" from a coffin into which his ashes have been spread, from blood dripping down from a poor victim (provided by Klove) Dracula is made to "manifest himself" over a period of about a minute. This was achieved by overlapping "dissolves" of a series of twelve locked-down camera shots, involving first the ashes, then a skeleton, then some body-fat on the skeleton, etc., along with swirling mist, till we finally perceive the full form of Dracula. He doesn't appear fully dressed as is usually the case - the shot moves to outside the coffin and a bare arm reaches out. The vampire's clothes were seen in earlier scenes awaiting his return.