In the original film, the cosmonauts are forced to improvise after one of three ships sent for the mission is suddenly destroyed by an asteroid strike. Two crewmen from one of the remaining ships, the Vega, decide to go down to the surface via glider along with their robot John. After they are blown off course, the crew of the remaining ship Sirius head down to rescue them, leaving only the mission's lone woman, Masha, to stay aloft and communicate with Mission Control.
At this point, what was previously a fairly hard sci-fi film takes a sharp turn to 1 Million B.C. territory, as the rescue team encounters carnivorous plants, dinosaurs, volcanoes and a mysterious sound like a woman singing...
Voyage to the Prehistoric Planet stays largely faithful to the original, though since this was the height of the Cold War, AIP scrubbed all signs of its origin by renaming the characters and leaving the Soviet cast and crew off the credits. Director Curtis Harrington also recast Masha (renamed Marsha) with American actress Faith Domergue, and visualized the previously disembodied voices of Mission Control as a small team led by Basil Rathbone.
Voyage to the Planet of Prehistoric Women, helmed by Peter Bogdanovich of all people, took more liberties by cutting Masha/Marsha completely and shoehorning footage of Mamie Van Doren leading a tribe of scantily clad women who are supposedly orchestrating the crew's difficulties in an attempt to get rid of them. This version also incorporated footage from another Soviet sci-fi movie that AIP had acquired, Nebo Zovyot, which had been heavily reworked into Battle Beyond the Sun for U.S. release.
Planet of Storms and its re-cuts include examples of the following tropes:
- Ancient Astronauts: Sirius crewman Alyosha/Andre argues in favor of this theory to explain signs of intelligent life on Venus, and his commander Vershinin/Lockhart later says that the ancient aliens could have visited Earth as well.
- Bridge Logic: As the Vega team tries to meet up with their Sirius crewmates, John fells a giant tree so that they can cross a chasm.
- Cargo Cult: In the Prehistoric Women re-cut, the Venusian tribe ends up worshipping the remains of John the robot.
- Convection Schmonvection: As a volcano erupts, John carries two men as he wades into a lava flow. Then the hover-car cruises right across the surface of the flow to rescue them.
- Cut-and-Paste Translation: AIP re-cut Planet of Storms to hide its Soviet origins and add some familiar faces for Western viewers. The first re-cut was fairly respectful, but the second...
- The Cynic: Allan Kern, who's prone to saying things like, "People are natural egoists and cowards" and "A robot can think, not a woman." Interestingly, Kern, who along with the similarly Anglo-named John comes from an "international association," is presumably meant to be American, and so is likely meant to contrast with Communist idealism. Not surprisingly, none of this subtext survived the U.S. re-cuts.
- Dub Name Change: All the Slavic names in the original were changed to Western ones for the re-cuts, although the already-Western Allan Kern and John remained the same.
- Emotions vs. Stoicism: When she loses contact with both teams, Masha/Marsha has an internal debate about whether to land the ship and try to rescue them, despite the fact that this would go against orders. "The instructions could not foresee everything. My heart tells me they need me more!
- Everything's Better with Dinosaurs: Venus harbors some mighty familiar-looking animals, including some giant sauropods, a pack of man-sized theropods, and a pterosaur that attacks the crew.
- Evolutionary Levels: The cosmonauts believe that an Age of Mammals following an Age of Reptiles is some kind of evolutionary law, leading to a debate when they find signs of intelligent life alongside dinosaurs (Ancient Astronauts are invoked).
- Human Aliens: At the end of Planet of Storms, we get a brief glimpse of a lovely woman who may be the source of all the mysterious singing. In Prehistoric Women, this gets taken Up to Eleven.
- Importation Expansion: This was fairly modest in the first re-cut, with some new scenes filmed to visualize the voices of Mission Control and one Soviet character replaced by a nearly identical American one. In the second re-cut, a whole tribe of Venusian women was added.
- Interplanetary Voyage: Depicts the first foray of human beings from Earth to Venus.
- Machine Monotone: John talks this way.
- Man-Eating Plant: Our first sign that the film is going to be more fun/silly than it looks is when a giant plant wraps its tendrils around Alyosha/Andre.
- Mission Control: In Planet of Storms Masha is in communication with headquarters which are offscreen but apparently on Earth, while in the U.S. version this is identified as "Lunar Base 7" and led by Basil Rathbone.
- Ms. Fanservice: A scantily clad Mamie Van Doren provides this to the second re-cut.
- Ptero Soarer: A goofy-looking pterosaur attacks the crew's hover-car as it crosses a body of water.
- "Second Law" My Ass!: While John generally tries to help the crew, he doesn't seem to be programmed to do whatever humans tell him. He reacts only when addressed politely, and when asked, "Where are your masters?" he responds, "No masters. Slaveholding is forbidden by the Constitution. I am a free, thinking machine." He also turns out to have a self-preservation program, which creates trouble for the humans later on.
- The Smurfette Principle: There's exactly one woman among the surviving crewmembers of the Venus mission.
- 20 Minutes into the Future: Since the film was made largely to get Soviets excited about their space program, it depicts a mission not too far removed from 1960s technology. The U.S. version specifies the year as 2020.
- Underwater Ruins: While the Sirius team is trekking at the bottom of a sea (or lake, it's not clear which) to escape the pterosaur, they find what looks like a sculpture of the exact same beast, though it's rough enough that one of them argues that it could be a natural formation. This happens to be in a cave near some suspiciously straight lines of cliffs, which also contains a small stone that turns out to have a carving of a woman's face inside it.
- Venus Is Wet: As was standard at the time, Venus is depicted as a cloudy, swampy place with at least one ocean.
- We Don't Need Roads: The Sirius has a landspeeder-like hover-car that can travel over pathless land as well as the surface of the sea. It lacks any submarine capacity, though, so when the crew submerge to escape the pterosaur they have to haul it along by hand.