Production notes

Fail Safe so closely resembled Peter George's novel Red Alert, on which Stanley Kubrick's film Dr. Strangelove was based, that screenwriter/director Kubrick and George filed a copyright infringement lawsuit. The case was settled out of court, with Columbia Pictures (which had financed and was distributing Dr. Strangelove) buying and distributing the independently produced Fail Safe. Kubrick insisted that the studio release his movie first. The character of Groeteschele was inspired, according to Lumet's audio commentary on the film, by Hudson Institute military strategist Herman Kahn. The US Department of Defense and Air Force declined any cooperation with the production, because its premise involved a lack of control over nuclear strike forces. At the end of the film's credits, a scrolling, full-screen textual message appears, rendered in a bold all-capitals font. The message reads, "The producers of this film wish to stress that it is the stated position of the Department of Defense and the United States Air Force that a rigidly enforced system of safeguards and controls insure that occurrences such as those depicted in this story cannot happen". Jazz musician Hal Schaefer wrote a score for the film. However, Sidney Lumet elected not to use it, instead having the film play without non-diegetic music (similar to 12 Angry Men). Snippets of the unused score can be heard in the film's trailer. Nonetheless, Columbia Records released a five-minute suite of Schaefer's score on vinyl record.

Because of the film's relatively low-budget (estimated at under $1.2 million), filming took place almost entirely in Lumet's hometown of New York City, with the key locations built as soundstage sets at Fox Movietone Studios on Tenth Avenue in Manhattan. The aircraft interiors were filmed aboard a modified training craft at LaGuardia Airport, where the exterior shots of Gen. Black boarding a plane to Washington D.C. were also filmed. Westbury, Long Island doubled for exterior shots of Washington D.C.. Cinematographer Gerald Hirschfeld was mainly known for shooting TV commercials. The "Vindicator" bombers are represented in the film by stock footage of Convair B-58 Hustlers, which could fly at twice the speed of sound. Fighters sent to attack the bombers are illustrated by film clips variously of the McDonnell F-101 Voodoo, Convair F-102 Delta Dagger, and Lockheed F-104 Starfighter. Stock footage was used because the Air Force objected to presenting the U.S. nuclear strike force being thrown into deadly disarray by an equipment malfunction and declined to cooperate in the production. A nightmarish quality is achieved by showing numerous flying sequences in photographic negative, as if being illuminated by a brilliant nuclear flash. In several of the negative sequences, the "Soviet interceptors" are actually French-built Dassault Mirage III fighters with Israeli markings.

When Fail Safe opened in October 1964, it garnered excellent critical reviews, but its box-office performance was poor.

Over the years, both the novel and the movie were well received for their depiction of a nuclear crisis, despite many critical reviews rejecting the notion that a breakdown in communication could result in the erroneous "Go" command depicted in the novel and the movie. The film's reception with both critics and the public was compounded by the prior release of the Stanley Kubrick nuclear war satire Dr. Strangelove, which had appeared in January 1964, nine months ahead of Fail Safe's October release. Still, the film was later lauded as a Cold War thriller. The novel sold well for the remainder of the 20th century, and the film was given high marks for retaining the essence of the novel. On review aggregator Rotten Tomatoes, the film holds a 93% approval rating based on 30 reviews. The website's critics consensus reads, "Fail-Safe strikes an impressive chord with its grim, high-minded exploration of the ultimate Doomsday scenario."

The film was nominated at the 1966 BAFTA Awards in the United Nations Award category.