Trivia: The hat band on John Wayne's hat once belonged to Gary Cooper. It was a gift to John from Cooper.
Trivia: All of the guards at the clinic on the mountain have the Olympic rings on their orange tracksuit tops.
Trivia: Peter Fonda meets up with two prostitutes in the film. One is Karen Black and the other Toni Basil who gave us that neat little hit Mickey in 1981.
Trivia: Katherine Ross, (Etta Place) was caught operating a camera, filming some footage of the arrival of the train carrying the "super posse". In the late 60s the US film business was strict, closed shop union (to a great extent it still is) and Ross operating a camera was against every rule there is. Several senior crew members demanded her dismissal from the film but producer John Foreman and Unit Production Manager Lloyd Anderson, aware of the fact that a lot of scenes with her in it would have to be reshot at absurd expense, argued for a compromise to which the union agreed - none of the footage she shot would be used (it wasn't) and she would be asked not to be on set while scenes in which she was not involved were shot. Her gender was totally irrelevant to the issue. This is confirmed in William Goldman's excellent memoir, "Which Lie Did I Tell?"
Trivia: Originally, Metro Goldwyn Mayer had planned for producer Roger Corman to make a film entitled "Captain Nemo and the Floating City," but the project collapsed early on. Producer Steven Pallos later resurrected the project as "Captain Nemo and the Underwater City," and this time the film was completed.