Flash jumping towards the camera screaming "YEAH!" was improvised by Sam J. Jones. Nobody could figure out how to end the movie.
All of the main cast members were signed for multiple films. The first movie didn't do as well as expected, so the sequels were never made.
Max von Sydow's Ming costume weighed over 70 pounds. He could only stand in it for a few minutes at a time.
Sam J. Jones' dark hair was bleached blonde, and Melody Anderson's blonde hair was dyed brown. Flash was supposed to have blue eyes, but Jones couldn't wear the contact lenses.
For the scene in which Dale turns into a giant spider for a dream sequence, Melody Anderson spent six hours getting painted green, wearing fake eyes and fangs, with a head piece that weighed over 20 pounds. When Mike Hodges came in, he said, "This is wonderful, but we can't use this! It has absolutely nothing to do with the script."