There are 31 individual insert shots of clocks in the movie. By contrast, High Noon (1952), also directed by Fred Zinnemann and more directly concerned with the passage of time, contains only 13 insert shots of clocks.
When the Jackal meets the weapons supplier in Genoa, there is a picture of John F. Kennedy on the cover of an Italian magazine reporting on President Kennedy's recent visit to Europe. The scene is set on 2 August 1963.
Michael Caine lobbied for the role of The Jackal, but director Fred Zinnemann did not want a movie star in the role as he thought that using a recognizable face such as Caine's in the role of a man who essentially is and remains a cipher would reduce the suspense felt by the audience. Thus, Zinneman offered the role to the lesser known Edward Fox, a move he reportedly regretted when the movie did disappointing business at the box office.
Near the end of the film there is a 7:45 segment with no dialog or music other than diegetic sound such as marching band music, crowd murmurs, sirens, etc.
When the Jackal looks at the hotel register to find out the name of Mme C. de Montpellier (about one hour and twenty minutes into the film), some of the names of other hotel guests can be seen. Some of them are crew members: L. Pitzelé (assistant director: France), René Strasser (chief grip: France) and William Holt (set designer: France).
The publication of the novel "The Day of the Jackal" and the releasing of the film two years later caused the Public Records Office and Passport Office in London to tighten up their rules to avoid (or at least lessen the chances of) anyone using the identity of a dead person.
Roger Moore revealed in an interview on Icelandic television in December 2005 that producer John Woolf allegedly wanted him to play the Jackal. Director 'Fred Zimmerman' rejected him since Moore was too popular from his role in "The Saint" (1962) and too tall. He wanted someone who could walk in a crowd and not be recognized or stand out.
Technical specifications and fold-out diagram for building the actual assassin's rifle are included with the hardcover Franklin Mint special edition of the novel.
The film features no soundtrack music other than diegetic background music from marching bands, street musicians and radios after the first five minutes.
During the filming of the final sequence where President de Gaulle is presenting medals to veterans, the large crowd of extras were unaware of how close a resemblance actor Adrien Cayla-Legrand bore to the actual President. On the first take, when the President exits his limousine, most of the crowd gasped and an elderly extra, who was playing one of the veteran soldiers, fainted in shock.
When the British find the bogus passport request it's mentioned that it was applied for on July 14. That is Bastille Day.
Presumably to avoid confusion with the names of living French people, the fictitious names used by Frederick Forsyth in the novel were replaced by those of famous French historical people: for example, Colbert (Louis XIV's Minister of Marine), Dumont (famous explorer), Berthier (Napoleon Bonaparte's chief of staff).