6. Phantom Empire (1935)
I never thought I would be able to say this, but there is a Gene Autry movie with a robot in it - unless you don't consider that cardboard cutout in the picture above to be a robot. The singing cowboy stumbles across the survivors of the ancient continent of Mu, which sank beneath the seas much like Atlantis. The Muranians are a peaceful folk, but us evil surface-dwellers want to acquire their supply of radium. Gene Autry must put an end to our greed and prevent an all-out war from stopping his radio show.
Estimated chance you've seen this one: 7%