Werner Herzog decided to restore the original names of the characters the day the copyright of the original "Dracula" expired, while still following the movie blueprint laid out by F.W. Murnau's Nosferatu (1922).
In order to get the restrained performance out of Klaus Kinski that Werner Herzog desired, he reused a trick from the making of Aguirre, la ira de Dios (1972). While Kinski wanted the play Dracula as more energetic, Herzog would provoke Kinski into a massive tantrum so he would be exhausted when the time came to shoot his scenes.
The film implies on several occasions that Dracula's castle exists in a type of shadow dream world and it is in this reality which Harker finds himself at the beginning of the film. This is implied by statements from the gypsies that Dracula's castle is in fact merely a crumbling ruin with these ruins seen while the sun is setting, although Harker finds himself in a fully intact castle. Harker himself even notes that the castle "doesn't seem real" and is haunted by the image of a violin-playing boy who is suggested to be either a phantom or ghost.
Klaus Kinski had to spend approximately four hours per day in make-up. Fresh latex ear pieces had to be poured for each day of shooting because they were destroyed at removal. Kinski, notorious for his violent daily temper-tantrums, had a very good relationship with Japanese make-up artist Reiko Kruk and was exceedingly patient and well-behaved during make-up. Kinski himself said of the make-up that he hated being excessively made up for a role, but for the role of Dracula it was important so he took it in stride. Kinski was so disturbed by his appearance in the make-up that he avoided looking in any mirrors during filming.
The exceedingly difficult slow-motion shots of a bat in flight were not shot by Werner Herzog's crew but borrowed from a scientific documentary.
Werner Herzog: (at around 54 mins) the person who sticks his foot into the coffin and gets his toe bitten by a rat.