Director/writer David Worth says that he was hired, shipped to Italy, and told to begin work on the film.... before he ever had a script. He was reportedly shown a poster for the film and told to make a film that would go with it.
David Worth explained in an interview that the story the poster existed before the movie is "apocryphal." This interview is available in the DVD extras for WotLW release as part of MST3K Volume 26 (XVI). In an on-camera interview Mr. Worth details how he was introduced to the producers and instructed to "make the movie" based wholly on his 40 page treatment.