In the original script, King Agamemnon was introduced as: "The warrior took off his helmet, revealing someone that looks exactly like Sean Connery, or an actor of equal but cheaper stature." To writer, producer, and director Terry Gilliam's surprise, the script ended up in Connery's hands. He expressed interest in the part, and his agent approached them for the role.
According to Terry Gilliam, David Rappaport believed he got his part for his acting ability alone, without size being a contributing factor. As a result, he didn't socialize with his co-stars. During the Invisible Barrier scene, when the other bandits retaliate against Randall, the actors were expressing their frustrations with Rappaport.
No studio wanted to make this movie, so executive producers George Harrison and Denis O'Brien mortgaged their office building in Cadogan Square to raise the $5 million to make it.
Ruth Gordon was cast as Mrs. Ogre, but was injured before production. Katherine Helmond was originally slated to play the role in heavy make-up, to look like her husband, but then decided it would be funnier if Mrs. Ogre was an ordinary person. Writer, producer, and director Terry Gilliam agreed.
Terry Gilliam: [cages] This movie uses cages identical to the cage in which Jill is imprisoned in Giliam's Brazil (1985).