The Phantom Empire is a 1935 serial starring Gene Autry (in his first leading role). The plot combined singing cowboy Autry and his friends at Radio Ranch with the science fiction happenings in the underground city of Murania (complete with imperious Queen Tika, elaborately helmeted guards, robots, death rays, and other accoutrements.)
- Footage from The Phantom Empire was used heavily in the second season Muppet Babies episode "Out-of-This-World History." When Gonzo takes the babies to Planet X, the footage is of Murania. Queen Tika (who spies on the babies with her viewing screen) is addressed by name in the new dialogue and refers to the planet as a "secret underground city" (as in the serial). She orders one of her robots to lure the babies to her.
- At one point, Fozzie points to shifty Lord Argo (also named in the dialogue) saying "He looks like a salesman." As story director Scott Shaw! recalled, "One episode was originally built around an old Flash Gordon serial; when the studio learned the rights were prohibitively expensive, it fell to myself to re-write and re-storyboard the entire revamped episode around footage from The Phantom Empire starring Gene Autry."
- On episode 202 of Muppets Tonight, the serial spoof "Lash Holstein: Space Cowdet" blended the space elements of Flash Gordon with the cowboy aspects of The Phantom Empire.