All the stock footage (as best as I could tell) from The Mysterians; Mothra vs. Godzilla; Ghidorah, the Three-Headed Monster; Invasion of Astro-Monster; Ebirah,...
Joel and the bots interacting with the movie in episode 212 of MST3k - Godzilla vs. Megalon....
Gigan returned in Godzilla vs. Megalon, as he was called by the Seatopians to help them conquer Earth. He arrived to help Megalon battle Godzilla, and they near...