The mutants were played by members of the Los Angeles Lakers.
Producer Ray Dorn "borrowed" much of this movie for Journey to the Center of Time (1967). Irwin Allen also borrowed much of the concept for his TV series The Time Tunnel (1966). Director Ib Melchior declined to make waves so he would continue getting work in Hollywood.
Forrest J. Ackerman's cameo appearance led him to make numerous cameo appearances, and even do bit parts, for more than 40 years.
Peter Strudwick personally contacted Ib Melchior about possibly playing the role of a monster in this film. After visiting Melchior at his house, Melchior wrote the part of The Mutant for Strudwick to specifically portray.
The film inspired the TV series The Time Tunnel (1966) as well as the remake Journey to the Center of Time (1967).
Production started in 1963, with the working title Time Trap. Ib Melchior's story line couldn't withstand the meager budget. Later reviewers regarded the production as secondary. "In spite of the low budget, this still looks pretty good thanks to intelligent use of the resources available. The portal the scientists create, as Danny discovers, is more than a mere window on the coming years, because they can actually walk through it and pass through the decades to exist in the future."
When the scientists discover that the future humans are travelling to Alpha Centauri, one scientist responds "25 thousand billion miles!" Alpha Centauri is about 4.37 light-years from our solar system, a little over 25 trillion miles.