The little hairy things that crawl across and that the Creatures eat are modified wind-up toy robots that run like crazy on two legs as a round rolling central body that houses the wind up motor. The wind-up key was removable.
The Special Edition DVD and the Blu-Ray disc feature several "workprint" takes showing early passes at dialogue. This early voice-over work differs from the final dialogue in several ways: the Skeksis speak in a foreign language, Frank Oz provided the voice of Aughra (sounding very similar to his voice work for Yoda in the Star Wars movies), and the Mystics were referred to by (presumably) their original name, the ur-Ru. The novelization was apparently based on this earlier version, referring to the "Trial By Stone" contest by its original name - "Hakskeekah" - and calling the Mystics the ur-Ru. In the final film, one reference to ur-Ru was not redubbed: when the Mystics enter the Skeksis Great Hall, SkekOk, the Scrollkeeper sees them and shouts "Ur-Ru!" Moreover, in the film's German dubbed version the Mystics are also referred to as ur-Ru. The filmmaker's decision to rename them came too late for the German dialogue track, which was already in the making at the time.
Pre-production work revolved around Brian Froud's designs without a finished script. When Froud originally presented Jim Henson with concept drawings for the crystal, Henson seemed totally perplexed. When Froud asked why, Henson said he had no idea what the designs were for. As it turned out, Froud had misunderstood Henson during early production conversations - Henson intended the film to be called "The Dark Chrysalis," referring to the Skesis dominance over the world. Henson, however, loved the concept art and integrated the idea of the crystal into the storyline.
Early drafts of the script featured Jen and Kira traveling through the underworld where they encountered a race of underground mining creatures. This concept was later integrated by Jim Henson into Fraggle Rock and served as the partial basis for the story of The Power of the Dark Crystal.
Jim Henson personally trimmed twenty minutes from the film after a disastrous preview in San Francisco. Henson also ordered many of the character voices re-dubbed to eliminate some of the invented character languages to make the film more accessible and the plot easier to follow.
From a budget of $15 million, the film made slightly over $40 million, a rather disappointing figure. This was put down to the fact that many parents felt the film was too scary for their children and also because it opened against the box office juggernaut that was E.T.: The Extra-Terrestrial.
Conceptual designer Brian Froud was behind the look and feel of virtually every aspect of the film's production, from creatures and landscapes right down to the font of the opening title. In total, it took up five years of his life.
Brian Froud's fascination with lobsters led to many crustacean touches in the design of the film, particularly in the design of the Garthim, the henchmen of the Skeksis.
Banned in strict Islamic countries due to content that was deemed "sacreligious" to the Islamic religion. Therefore, every Arabic-dubbed and Farsi-dubbed copy was destroyed by the censors.