This is one of the highest-grossing Swedish movies of all time, being released in more than 54 countries and even achieving cult status in Asia.
Menaham Golan & Yoram Globus passed on releasing this film for the producers, who were looking for a global distributor to print their film for a worldwide theatrical release, mainly targeting U.S. audiences due to the sudden Ninja Craze that was starting to arise. The Cannon Group executives decided to pass on this film (due to the film "not having enough "Ninja Action" and lack of American actors") in favor of producing and releasing a ninja film of their own, American Ninja (1985).
The so called "Leningrad University" is actually Lidköping City hospital. Most of the fight scenes were done inside the hospital too.
According to director Mats Helge Olsson, then-unknown Jean-Claude Van Damme applied for a job as an extra in this movie.
The music was made with a drumulator, two synthesizers and 4-track wheel to wheel recorder. It was composed produced and synced to the film as it was cut. The last pieces of music at the end of the movie was recorded at filmstaden Stockholm, in parallel with the final mixing of the soundtrack.