When Jeff Bridges walks outside the house naked and uses a 'marble' his hair seems to stand on end. This effect was actually created by shooting Bridges hanging upside-down and then matting the shot onto the background the right way up to give him a surreal look.
This script was being developed at Columbia at the same time as another script about an alien visitation. The studio did not want to make both, so the head of the studio had to choose which film to make; he decided to make this one and let the other script go to a rival studio. The other script was for E.T. the Extra-Terrestrial.