Writer/director Edward Bernds first sought Sterling Hayden and then Frank Lovejoy for the lead. Producer Richard V. Heermance eventually hired Hugh Marlowe, who asked for only a quarter of the other actors' salaries. According to Bernds, Marlowe was often lazy and unprepared.
This film was produced directly by Allied Artists (formerly Monogram Pictures). It was made in hopes of shedding Monogram's "poverty row" image. It was given a larger budget, shot in color and CinemaScope and ran a full reel longer than their usual 60- to 70-minute running time common to "B" pictures. Allied Artists was able to book it under percentage contracts rather than flat rates.
Writer/director Edward Bernds disagreed with first-time producer Richard V. Heermance's budget-saving practices, especially the economically filmed final scene.
According to writer/director Edward Bernds, cost-conscious producer Richard V. Heermance wanted to do a science-fiction film in order to take advantage of some stock footage from Monogram's Flight to Mars (1951), which Bernds said could have been re-shot for a few thousand dollars and would have looked far more authentic than the stock footage.
Just four years later, one of this film's stars, Rod Taylor, would star in George Pal's The Time Machine (1960). Based on the novel by H.G. Wells, this film would be Rod's second foray through time in his career.
In this film, Rod Taylor still retains traces and phrases from his Australian background. By the time he filmed "The Time Machine", just a few years later, he'd lost all vestiges of his home country.
The title is derived from the modern Anglican version of a Catholic devotional doxology: "Glory to the Father and to the Son and to the Holy Spirit; as it was in the beginning is now and ever shall be, world without end. Amen."
Although the films had nothing in common except time travel, the H.G. Wells estate sued the producers for plagiarism, citing similarities to Wells' novel "The Time Machine". Ironically, the producers of the film made from that story, The Time Machine (1960), used Rod Taylor, who starred in this film.
Writer/director Edward Bernds reused the motorized spiders in Queen of Outer Space (1958) and Valley of the Dragons (1961).
With the death of Nancy Gates in March 2019, Lisa Montell became the last surviving member of the credited cast.
Writer/director Edward Bernds claims he invented the word "mutate" in this picture although, he admits that "mutant" has become much more popular.