Although the onscreen credits contain an exclamation point in the film's title, most contemporary sources referred to the picture only as Zero Hour. The film begins with a voice-over foreword, spoken by William Conrad, explaining that Ted Stryker, the lead character in Zero Hour!, was a Canadian squadron leader in the Royal Air Force during World War II. Ordered to bomb Axis supply depots in Wiesbaden, Germany, Stryker failed to abort the mission when fog suddenly enveloped the city, causing his planes to become disoriented and crash into the ground. Though Stryker survived his injuries, six of his men were killed. At different times in the film, Charles Quinlivan's character is referred to as "Harry Burdick" and "Harry Ballard."
       Newt Arnold and Lee Lukather, who are listed onscreen as "Assistant to the producer" and "Production manager," respectively, are listed by some contemporary sources as assistant directors. According to the Var review, Zero Hour! was the first film by the new independent film consortium of director Hall Bartlett and producer John Champion. Although HR news items state that the film was to be the first in a two-picture deal between Bartlett-Champion and Paramount, the pair did not produce any other films together.
       According to the file on the film in the Paramount collection at the AMPAS Library, Zero Hour! was produced at the cost of $400,764, including $21,000 for the screen rights to Arthur Hailey's teleplay, entitled Flight into Danger, which aired on NBC's The Alcoa Hour on 16 Sep 1956, and starred Macdonald Carey and Patricia Barry under the direction of Herbert Hirschman. The film version marked Hailey's first feature-length screenplay. Hailey went on to become a highly successful novelist in the 1960s, with film adaptations of his work including the 1967 Warner Bros. film Hotel and Universal's 1970 release Airport (see entries in AFI Catalog of Feature Film, 1961-70).
       According to LAT news items, Harrison Reeder of Robert Alexander Productions attempted to purchase the screen rights to Hailey's story as a star vehicle for actor Steve Cochran, but was outbid by Bartlett, who purchased it five days after the television production was first broadcast. HR news items at that time state that Bartlett had intended to produce the film in association with Sam Weiler, but Weiler received no screen credit in Zero Hour! and his contributions, if any, to the released film have not been determined. Paramount studio records also indicate that footage of actor Dana Andrews was purchased by Paramount from Twentieth Century-Fox for Zero Hour! The footage, used in the film's opening sequence in which Andrews portrayed a World War II pilot, may have been taken the 1944 Fox film Wing and a Prayer (see AFI Catalog of Feature Films, 1941-50). According to a 24 May 1957 HR news item, portions of the film were shot on location at an airport in Santa Ana, CA.
       Nightclub and television performer Peggy King made her feature film debut in Zero Hour!. Paramount press materials report that King recorded the song Zero Hour on Columbia Records in conjunction with the film's release. The picture also marked the feature film debuts of Charles Quinlivan, Carole Eden, Steven London, Jo Ann Wade and Raymond Ferrell. Although the credits imply that John Ashley made his screen debut in Zero Hour!, he also appeared in the AIP release Dragstrip Girl, which was released earlier in 1957.
       According to a Jun 1957 LAEx article, Harold Cope, the film's technical advisor, was an executive with American Airlines. HR news items include Robert Brubaker, Duane Grey, Cyril Delivanti, George Selk, John Zaremba, James Maloney, Sheila Noonan, John Launer and Joe Perry in the cast, but their appearance in the released film has not been confirmed. Modern sources also include Woody Chambliss in the cast.
       In 1971, Hailey's story was filmed a second time for television under the title Terror in the Sky, directed by Bernard L. Kowalski and starring Leif Erickson and Doug McClure. Zero Hour was also the inspiration for the 1980 film parody Airplane!, which starred Robert Hays as "Ted Stricker" and Julie Hagerty as "Elaine" and was directed by Jim Abrahams, David Zucker and Jerry Zucker. The great success of that film led to a sequel in 1981, Airplane II, The Sequel, and spawned numerous similar film parodies.