Now, Voyager

Voyage to a Prehistoric Planet (1965) is a ridiculous artifact: It started life as a Soviet science fiction film about a trip to Venus, a planet of savage reptiles and hints of a humanoid civilization. Then, Roger Corman's production company got a hold of it. They took out most of the spaceship special effects, because the ships had Soviet red star insignia. They added in scenes with Faith Domergue (of course) and Basil Rathbone (!?!) as ground or orbital control, talking to the cosmo astronauts on Venus remotely. Heavens knows what they did to the plot.

The bulk of the Soviet material makes a pretty decent space opera. The savage reptiles are a bit hokey, but the robot and the flying car are actually pretty neat. The Domergue/Rathbone inserts are not intrusive - surprising how well they fit, but I suppose that's the kind of thing they were good at.

I understand there is another version, Voyage to the Planet of the Prehistoric Women, with Mamie Van Doren and a bunch of bikini girls padding the film instead of Faith Domergue, an early directorial attempt by Peter Bogdanovich. It's in my DVD queue, but I don't know if it should be.