Tin Pot
Guru
Troglodyte humans? That would be The Time Machine, I think.
(Confession: I once went to a day long marathon of all the original Planet of the Apes films. There were five, as I recall, including some that weirdly got future apes into present day USA, which makes no sense. It was a long time ago, but I don't remember any underground humans)
Yeah - how did that happen? I seem to remember them running around an old wwii ship.