Henry Brandon hoped to play chief villain Killer Kane but was cast as Kane's henchman Captain Laska instead. When Brandon complained to his agent about this, he was told, "The lead heavy works for one day, the henchman works for three weeks. Which part did you say you wanted again?"
Chapter Titles:
- 1. Tomorrow's World
- 2. Tragedy on Saturn
- 3. The Enemy's Stronghold
- 4. The Sky Patrol
- 5. The Phantom Plane
- 6. The Unknown Command
- 7. Primitive Urge
- 8. Revolt of the Zuggs
- 9. Bodies Without Minds
- 10. Broken Barriers
- 11. A Prince in Bondage
- 12. War of the Planets
Forty years later, Buster Crabbe made a cameo appearance as Brigadier Gordon in Planet of the Slave Girls (1979). As they fly into battle, Gordon tells Buck (Gil Gerard), "I've been doing this since before you were born." When Buck, at 533-years-old, asks "You think so?", Gordon's answer is a confident "Young man, I know so." The name Brigadier Gordon is a reference to Crabbe's most famous role as Flash Gordon in Flash Gordon (1936), Les nouvelles aventures de Flash Gordon (1938) and Flash Gordon Conquers the Universe (1940).
The bullet cars used in the movie were the same ones used in Les nouvelles aventures de Flash Gordon (1938).
The character of Killer Kane was changed: in the original strip, his name was Coe Kane, and he had a twin brother named Nova and a pistol called "Baby". He also had a girlfriend named Ardala Valmar. A former suitor of Wilma Deering, he became a traitor to the Americans who struggled against the Han. In the serial, he became the easily-identifiable villain "Killer" Kane, presented as the despotic ruler of a future Earth.