Undersea Kingdom is a 1936 movie serial produced by Republic Pictures to compete with Universal Studio's Flash Gordon series. It marks the first appearance of the "Republic Robot" which was used in several Hollywood films including Mysterious Doctor Satan (originally scripted as a Superman serial, and spoofed sixty years later on Star Trek: Voyager's recurring "Captain Proton" stories).
- A short clip from the sixth chapter in the series was used in the Muppet Babies episode "From a Galaxy Far, Far Away..." Amidst a sequence making heavy references to The Day the Earth Stood Still, Baby Gonzo opens a closet door to footage of robots from the movie on the march for invasion.
- Another series of clips were used in "Journey to the Center of the Nursery" where the Babies use a tank from the film to get around under the surface of the Earth. A squadron of robots from the film act as guards over the Babies as they're forced into salt mining.