Because of a strike by the Screen Actors Guild, filming was shut down in July 1980 (along with numerous other motion picture and television series). The strike ended at the beginning of October 1980 (filming had started in June).
The weather at the Colorado shooting location caused Stan Winston's elaborate robot makeups - which took several hours to apply - to gradually wilt in the heat, limiting how much footage could be shot in a day.
Andy Kaufman, increasingly bored with the proceedings and having no friends to goof off with between takes (his friend/co-conspirator Bob Zmuda was specifically prohibited from the shoot), began acting out onset.
Andy Kaufman felt that the movie was so bad that he personally apologized for it on Late Night with David Letterman (1982), and as a joke promised to refund the money of everyone who paid to see it (which didn't involve many people). Letterman's response was that if Kaufman wanted to issue such refunds, Kaufman had "better have change for a 20 (dollar bill)".