When Germany was reunified on 3 October 1990, the cast and crew of this film were filming on location in Italy, so in fact, Wolfgang Stumph, Marie Gruber and Claudia Schmutzler left their home country as citizens of the German Democratic Republic and came back as citizens of unified Germany.
Because no one thought of shooting a 'Making of' or something similar, Wolfgang Stumph allowed the production company to use private video tapes he had shot on the set in 1990 for the "Behind the Scenes" material on the DVD release of this movie and its sequel.
When André Eisermann was cast for the film (it was his first film role ever), director Peter Timm advised him to avoid sunlight, so he would look as pale as possible for his role as a computer geek. When Eisermann went to a holiday trip to Majorca before filming, he spent most of his time there reading in his hotel room.
Claudia Schmutzler fell ill during filming in Italy and was actually too sick to film the dancing scene on the shore of Lake Garda, but decided to shoot the scene anyway. When Marie Gruber learned that the filmmakers had allowed this, she went straight to them and complained heavily. As Schmutzler said after Gruber's death in 2018, this incident lead to Gruber becoming some kind of blacklisted among filmmakers in reunified Germany.
André Eisermann had to speak with a Bavarian accent for the film; but as he was not a Bavarian, cinematographer Axel Block had to help him how to pronounce his lines properly.