According to Dennis Gansel, the vampires each represents a time in German history he thought where a high point Louise represents the lat 1700's, Charlotte the 1920's and the golden age of German films and Nora the 1990's after the fall of the Berlin wall.
Nina Hoss was always the first and only choice as Louise when Dennis Gansel wrote the script in 1999. She wanted the part from the get go. Karoline Herfurth had also been attached since the 90s but was too young to play Lena, the part Gansel wanted to give her. Instead he promised her the part of Nora. Due to the delay in production, however, Herfurth was old enough to play Lena when the film was finally green-lit.
The word "vampire" is not said once in the entire film.
Due to the tight budget and not being able to afford to many shooting days, five cameras where rolling at the same time to get all the footage needed.
Jennifer Ulrich prepared for the role of Charlotte by watching her favorite vampire films Interview with the Vampire: The Vampire Chronicles (1994), Blade (1998) and Underworld (2003) and read a biography on Asta Nielsen. She used Angelina Jolie as a base for her performance.