This is a 1961 fantasy sci-fi film that was directed by Edward Bernds. It stars Cesare Danova, Sean McClory and Joan Staley.
Two European men are about to fight in a life or death duel, while in a Algeria on expedition. The dispute was over a woman and they were about to shoot one another and then disaster struck. A comet hurtles towards Earth and sends out a shockwave, blowing everyone away but the two main characters manage to keep holding on. When the comet itself leaves, the men realise that they're not where they should be. Everything has gone but instead there's jungles, dinosaurs and Stone Age people.
This interesting adventure flick is based on an 1878 Jules Verne novel called "Hector Servadec" or "Career of a Comet." The novel itself explores far more depth of rational people trying to understand where they are. The comet itself is called Gallia which has become the new home world of the survivors complete with oxygen, animals, more humans, monsters and plants. While the film does explore possibilities about space and how they're really on the comet because of the Earth being visible in the sky. Parts of the film used some materials from the 1940 film "One Million Years BC". There has never really been any recent adaptions of the story apart from the Australian animation titled "Off on a Comet" made in 1979.
I rate this unknown little gem a 8/10. Spoiler and also my comment below.
Blood Strawberry
Spoiler: The Internet Movie Database wrote that the two men are taken to the moon, but they're actually living on the comet. The characters discuss when the comet will return to the earth again and they all hope this will be their chance to go home.