Original director William Berke died of a sudden heart attack on the first day of shooting. His son, Lester Wm. Berke, took over.
The concept of the atomic-powered cruise missile doomsday weapon was similar to that of the U.S. Air Force's Supersonic Low Altitude Missile, which was under development at the time.
Scenes of Ottawa residents entering shelters were either shot somewhere in Canada or the property master had an eye for detail: the shelter signage is in both English and French (shelter/abri).
The film refers to Havenbrook Atomic Laboratory in suburban New York City. The actual Brookhaven National Laboratory is in Brookhaven, L.I., N.Y.
Passed by the British Board of Film Censors with an "A" certificate on 6 October 1958. Enjoyed a two week run in London's West End, opening at the London Pavilion on 21 November 1958 and sharing the bill with Timbuktu (1958). Both films were generally released at normal prices on 14 December 1958.