The producers of this movie were sued by Robert A. Heinlein, who claimed the plot stole several elements of his novel, "The Puppet Masters". The suit was settled out of court. Producer Ed Nelson, who also stars, created the parasites himself using little wind-up toys covered with fur from an old coat and pipe cleaners for antennae. Some sources have claimed that future exploitation director Jack Hill acted in this film. "Jack Hill" was actually the name being used by veter ...[Read Story ]