The Time Travelers (1964 film)

The Time Travelers aka Time Trap is a 1964 science fiction film directed by Bmovie director Ib Melchior. It stars Preston Foster, Philip Carey, Merry Anders, Steve Franken, John Hoyt and Delores Wells. The cast also includes superfan Forrest J. Ackerman in one of his many bit roles in science fiction films. The film inspired the 1966 TV series The Time Tunnel as well as the 1967 remake Journey to the Center of Time. The plot involves a group of scientists who find their timeviewing screen allows them to travel through time. American International Pictures released the film as a double feature with Atragon.

As the setting is becoming unstable, the others enter the portal to bring him back. The portal disappears, stranding them. Then they are pursued by hostile primitives, ending up in a cave. There they find an underground city all that is left of civilization in a future devastated by nuclear war.The year is 2071 A.D. City leader Dr. Varno John Hoyt explains that Earth is unable to support life. The residents are frantically working on a spacecraft that will take them to a planet orbiting a distant star. The four time travelers pitch in to help complete the spaceship, but before they can lift off, the degenerate mutant humans break in and destroy the ship and the city. ........

Source: Wikipedia