Terry Gilliam was afraid that Brad Pitt wouldn't be able to pull off the nervous, rapid speech. He sent him to a speech coach but in the end he just took away Pitt's cigarettes, and Pitt played the part exactly as Gilliam wanted.
Terry Gilliam gave Bruce Willis a list of "Willis acting clichés" not to be used during the film, including the "steely blue eyes look".
Bruce Willis took a lower salary than his star-status would normally entitle, partly because of budget restrictions, but mostly because he wanted to work with Terry Gilliam. Actually Bruce did the movie for free. It was only after the movie was released that he was paid.
Although never addressed directly in the film, the script and some promotional material reveal that the future scenes take place in the year 2035.
Director Terry Gilliam first met Bruce Willis while casting his film Fisher King - Le roi pêcheur (1991). He was impressed by the sensitivity shown by Willis in the scene from Piège de cristal (1988) where McClane (Willis) talks about his wife while pulling glass from his feet. Talking to Willis, Gilliam discovered that this part was ad-libbed by Willis. Gilliam remembered this, and was convinced to cast him in this film.