Acting for Two: Candy Clark plays both Mary-Lou and the wife Thomas left behind. This isn't obvious because the latter is a Rubber Forehead Alien who has no dialogue. (She also played Thomas himself in one scene, with a hat pulled over her face, when David Bowie was ill.)
Now, Ziggy Stardust was an alien on Earth And he was doomed To fall to human vice, and leave his people blue Director knew! Nicholas Roeg must have known 'bout this Banned from space, this is a case Of casting your actor... based on his works!
The novel was primarily set in Kentucky, but the movie used New Mexico to take advantage of a tax break for British filmmakers (this was the first British-produced film shot entirely in the U.S.). Its deserts also provided a useful backdrop for the scenes set on Newton's home planet.
Bowie originally was tapped to write the score and worked on it with Paul Buckmaster. For various reasons, it wasn't used and has never been formally released, though a backwards bass part on Low's "Subterraneans" was taken from what they worked on.