The word "vampire" is not said once in the entire film.

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.

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.

Jennifer Ulrich prepared for the role of Charlotte by watching her favorite vampire films Wywiad z wampirem (1994), Blade: Wieczny łowca (1998) and Underworld (2003) and read a biography on Asta Nielsen. She used Angelina Jolie as a base for her performance.

The inscription on the ceiling in the prison cell reads: "Sie befinden sich im Revier 38. Neukölln. Berlin. Deutschland. Europa. Erde." ("You are in station 38. Neukölln. Berlin. Germany. Europe. Earth.").

The scenes set in the hotel lobby were shot in the local district court of Berlin Mitte. The location was available for one night only and the team was still filming when the first prosecutors came to work.

Dennis Gansel got the idea for the movie while walking home to his apartment in Berlin after watching Szkola czarownic (1996). He came across a large abounded building and thought it was curious that such a place existed in Berlin. While walking home he began to fantasize about what could be going on in there. When he came home, his then girlfriend showed him some photos she had taken. There had been something wrong with the photos during the processing and the photos looked rather ghastly. And then the ideas came together in Gansel's head.

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.

At first the vampire teeth where complete bridges in the mouth which gave the actresses a undesirable lisp. Georg Korpas solved the problem by using glue-on teeth. Jennifer Ulrich actually forgot at times that she had fake teeth in her mouth.

At the very end of the closing credits you can hear Charlotte say "Miau".

During Lena's transformation scene, her hair was not supposed to grow out. Only the dye was to go away. The hair growing back was added since the shot was not effective enough. This made the shot very complicated to get right.

According to Anna Fischer the fake blood the vampires frequently drinks cause diarrhea when they had to much of it.

Louise has plans to travel with her courtiers to Moscow. This is of course where Dennis Gansel's next film, Die vierte Macht (2012), takes place.

The scene on the bridge was supposed to take place on a sunny summer day. The day of shooting it was a cold autumn day and it rained.

Jennifer Ulrich wanted there to be as much blood as possible.

Much of Louise more antagonistic scenes were scrapped in editing to make her character more sympathetic.

With the exception of Tom & Lummer, none of the male characters have more than three lines.

The licence number of Nora's car is FU-CK 1.

According to the police file on Tom's computer, Lena's surname is Bach.

Dennis Gansel had a cameo in the film, like he usually does, as a police officer. The scene was deleted. In the scene he had one line before his character got his throat viciously slashed by Louise.

Dennis Gansel slept to little during production and overworked himself so much he had to wear make up so no one could see how terrible he looked.

Christian Becker has stated that this film is his and Dennis Gansels most personal movie.

There are 200 digital effect shots in this film.

A deleted scene revealed Lena's mother's name to be Lili and the probation officer's to be Dietmar.

The song "Au clair de la lune" that Charlotte sings and is used as her theme is the first song ever recorded and also the first sound ever recorded. It was recorded in 1860 by Édouard-Léon Scott de Martinville.

Max Riemelt and Arved Birnbaum play two police officers in this film. They did the same in the acclaimed TV miniseries Im Angesicht des Verbrechens (2010).

The director and many of the lead actors had worked together before. This film is Max Riemelt's fourth collaboration with Dennis Gansel. He also starred in Dziewczyny, dziewczyny (2001) (which also starred Karoline Herfurth) and in Fala (2008) which also starred Jennifer Ulrich. Herfurth also starred together with Riemelt in Mädchen Mädchen 2 (2004) and with Ulrich in Große Mädchen weinen nicht (2002). Ulrich and Anna Fischer both starred in Chmura (2006). Nina Hoss and Jennifer Ulrich both appeared in Czastki elementarne (2006).

In the Mädchen, Mädchen-series Karoline Herfurth also plays a character named Lena. The first film in that series was directed by Dennis Gansel.

Jochen Nickel had a larger role in an early cut. There was a whole subplot about Lena bribing him and due to the failed card theft she did not have enough money to pay him. In the final film all his dialogue but one line was cut, making him little more than a featured extra.

Dennis Gansel wrote the first draft in 1998.

Jürgen Vogel visited the set during the shooting of the climax. He gave Dennis Gansel a massage.

Dennis Gansel: [Actor] Max Riemelt.

Dennis Gansel: [Suicide]

The book Charlotte is reading is "For Whom the Bell Tolls" by Ernest Hemingway. The novel brings up suicide as an alternative to suffering, foreshadowing what happens to her later in the film.

In a deleted scene it's said straight out that Louise allows Lena to kill her at the end where as the final cut only hints at it.

Dennis Gansel wanted to shoot the film in 2006 but financiers said no thus Gansel went on and made Fala (2008) instead. As a side effect, many ideas that originated in "Wir sind die Nacht" also ended up in "Die Welle", giving the films thematic similarities. The most notable examples are the fact that both films feature a main character who has a single mother and does not care for them and the ending; both "Die Welle" and "Wir sind die Nacht" end with a character seeing something hidden from the audience. In "Die Welle", the character is frightened while in "Wir sind die Nacht" he is relived of what he sees.

The last scene to be shot was Louise's death scene.

The scene where Charlotte burns to death was originally going to be much more gruesome but Dennis Gansel requested that the scene was toned down.

In Dennis Gansel's previous film Fala (2008), Max Riemelt and Jennifer Ulrich played lovers. In this film they have one scene together, in which Riemelt's character ends up shooting Ulrich's character.