At the time of filming, Julia Heydkamp was 15 and Tabitha Deipenbrock was 16. Both of them have nude scenes.
The mass scene in the gymnasium was filmed in Villigen on 9 May 2010 and to find the extras, an advertisement was placed on various websites in addition to the official film website. The ad said that they were looking for 1,000 naked young women who did not want to miss the chance to be part of the project. Many came forward (although less than 1000) and all of them were involved in the nude scenes, always filmed frontally and with their genitals exposed, almost all of them having their vulva shaved. Some of these extras actually entered the film, in the scene in which they carried Armin on a litter and in the one in which they performed various gymnastic exercises.