The film is based on a true story although the sisters in question were handball players rather than rowers. One of the two genuine sisters is one of the producers of the film and contributed to the screenplay.
Luise Heyer, who was a theater actress, was cast at the last minute after the actress initially cast became pregnant. It became her breakthrough cinema role.
In order to portray the closeness of the twin sisters, both actresses had to adjust their natural gait, one to take smaller steps, one to take larger ones, until they walked with the same gait.
The actresses portraying the twins, neither of whom had any experience in rowing, spent a month learning to row in unison before principal photography began.
Luise Heyer's debut.