Okay, bear with me. This gets complicated.
Pavel Klushantsev directed a Russian sci-fi film called Planeta Bur in 1962.
In 1965, it was dubbed into English, re-edited and new scenes starring Basil Rathbone and Faith Domergue were filmed by director Curtis Harrington. It was released as Voyage to the Prehistoric Planet and Harrington was so happy with the result that he took his name off the credits and used the pseudonym "John Sebastian."
In 1968, the Harrington version was re-edited again. The Rathbone/Domergue scenes were removed and replaced with new scenes starring Mamie van Doren shot by a new director. This version was called Voyage to the Planet of the Prehistoric Women. Also deciding to keep his name off the credits as well, the new director, Peter Bogdanovich, would soon be nominated for two Academy awards for directing and writing The Last Picture Show. (Bogdanovich also served as narrator for his version of Voyage.)
(And please don't be confused by World of the Prehistoric Women, a 1966 film with John Agar which has nothing to do with any of this.)
Got all that? There will be a quiz.
Let's start with Voyage to the Prehistoric Planet.
The opening narration: "The year: 2020. The Moon has been explored and colonized and the next space goal is about to be reached - the first landing by on the planet Venus. Scientists profoundly hope that life, similar to that on Earth, may be found on this planet where so many physical conditions are like our own."
If they thought Venus was like the earth, it's no wonder the Soviets lost the space race.
But seriously folks, the film is about the first manned landing on Venus. Five astronauts and a robot explore the planet. They are attacked by creatures that look exactly like guys in small Godzilla costumes, and a giant flying reptile. The robot dies in a lava flow.
What's really cool is that the astronauts drive around in a floating bubble car similar to that car Homer drove in that episode of The Simpsons. Actually, some of the production values are fairly decent, and the robot has some ingenious design features. Still, the film is slow and ponderous, and the dialogue is often stilted, but this is probably due to the attempt to match lip movements during dubbing. Ultimately, it's a strange curio -- it doesn't have the camp value of many low budget sf films, and it's interesting look at how "the other side" approached sf films in the 1960s. Worth a look if you see it lurking at your local rental store.
The second re-edit, Voyage to the Planet of the Prehistoric Women, is pretty much the same movie as the first one. All the dubbed Russian scenes are the same at first, but then suddenly the astronauts start talking about Venus being the goddess of love. What were they going to find there?
They keep hearing female voices calling them, and we cut to seven beautiful women lying on a beach who suddenly decide to go fishing. They dive into the ocean and grab fish in their hands and eat them raw. I guess that's what makes them prehistoric. So as our Russian heroes continue with the story as told in the first version, we now have the "sirens of Venus" subplot that adds an extra 10 minutes to this film. (There may even be more, as all the previous English scenes with Rathbone are gone, and I think the Russian scenes have been tightened up. But I'll be damned if I'm going to waste even more of my life comparing the two versions even more closely.) Anyway, the sirens want the earth dudes to leave Venus so they are working behind the scenes to engineer all the plot complications that appeared to be simply natural in the first version. While it's an interesting lesson in how a film's tone and tempo can be altered through restructuring and editing, the second version doesn't hold up as well. Still, it does manage a little twist at the end, and is not entirely without merit.
But only just.