Sam Francisco (Mandy Patinkin) was originally going to be named George Jetson, but Hanna-Barbera wouldn't give the rights to the name. The decision to call his character "George" in the movie was kept as an in-joke to the George Jetson character name.
When James Caan was asked about this film during an interview with the AV Club in 2013, he replied, "Why the f****...Why would you bring up that?" The interviewer Will Harris said, "A lot of people actually like the film. I do, for one." Caan continued, "Yeah, well, I don't know. I don't have too many...I mean, I loved Mandy Patinkin. Mandy was a riot. But...I don't know. It was a lot of silly stuff, creatively. And we had this English director [Graham Baker] who I wasn't really that fond of. I mean, nice guy, but...it was just one of those things where, you know, you don't quit, you get through it. It certainly wasn't one of...I wouldn't write it down as one of my favorite movies. But it was pretty popular."
The October 1987 draft of the screenplay credits a re-write to James Cameron, but Cameron is not credited in the final film.
It took four hours per actor to apply the alien makeup.
The movie spawned a short-lived television series Missão Alien (1989) which ran for about a year. The picture and its subsequent series also spun off five television movies during the 1990s: Missão Alien 2 (1994), Missão Alien 3: Corpo e Alma (1995), Missão Alien: Novo Milênio (1996), Missão Alien: O Inimigo Oculto (1996), and Alien Nation: The Udara Legacy (1997). Also created was a series of comic books and novels.