Even the child actors didn't know during the shooting, that the role of Kurt was played by a girl, Birgit Komanns. Director Wolfgang Becker introduced the actress to the cast as Bernd Komanns, which is a male name.
None of children playing the members of the suburban crocodiles were professional actors. Birgit Komanns ("Kurt Wolfermann") was cast from a school for handicapped people in Bergisch-Gladbach, all the others were local kids from Bracht, a part of town of Brüggen in North Rhine-Westphalia, where the movie was filmed. Apart from appearing in the documentary Bleibt knackig, Freunde! (1982), none of them ever took an acting job again.
In a 2004 interview, Heiner Beeker, who plays Frank, talked about the famous scene where Kurt has to go to the toilet on the way and the boys can't handle it:
"Oh, that was embarrassing! Absolutely! None of us wanted to be there, but it was in the script. We were already wondering during the rehearsals who would have to open Kurt's fly. It wasn't clear at the time of filming either, it was decided at fairly short notice. Our Birgit [Komanns] had a double with her, a young stuntman who was used for all the falls with the wheelchair. He also played the "pee scene". First you see Kurt being lifted out of the wheelchair, cut, and then you only see him from the trouser belt. I don't know whether Rita [Ramachers], as Maria, knew beforehand that she was supposed to open his pants. In any case, she somehow managed it with a very red face. We would have preferred to continue on our bikes, but Wolfgang [Becker] wanted us to stand there and watch. It was very important to him, but we were embarrassed. I know that for a fact, it wasn't for us boys, nobody wanted to do it! How he persuaded Rita to do it remains a secret between the two of them."