Director Fred Zinnemann wanted the Jackal to be played by someone anonymous and indistinct, so he eschewed famous names in favour of casting a then-unknown actor named Edward Fox. He later admitted this concept may have led to the film's lack of expected success when it released in theatres.
(at around 24 mins) 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, about three months before Kennedy himself was assassinated.
During the filming of the final sequence where President de Gaulle is presenting medals to veterans, the many 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.
(at around 8 mins) Casson mentions the Jackal having done "that fellow in the Congo". He probably refers to Patrice Lumumba, the first Congolese president, who was rumored to have been assassinated by a European; this also alludes to Frederick Forsyth's third novel, 'The Dogs of War', which focused on European soldiers (mostly mercenaries) getting involved with African affairs (conflicts commonly) back in the 1960s-70s.
The film features no soundtrack music after the first five minutes other than diegetic background music from marching bands, street musicians and radios. Fred Zinnemann deliberately refused to use it on the grounds that soundtrack distracts the movement and tension generated.
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).
The first scene filmed was the Jackal's meeting with the OAS members. It took three days to shoot, as Edward Fox was having a hard time getting into the character. Director Fred Zinnemann eventually realized that he was concentrating too heavily on the scene. He and Fox took a long car ride, and he assured Fox that it wouldn't harm his career if he didn't get it right, since he had been Oscar-nominated. They went back to the set and filmed the scene effortlessly.
The Liberation Day scenes were filmed at a real parade, with most spectators being unaware of a film being shot. This caused a bit of confusion: many of the crowd mistook the arrests being filmed for real ones, and attempted to assist.
(at around 8 mins) One of the Jackal's targets was a man named Trujillo. This is likely Rafael Trujillo, the president of the Dominican Republic, who was considered a tyrant and a dictator and who was assassinated in 1961.
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.
(at around 1h 24 mins) When the Jackal looks in the hotel register to find out which room Madame de Montpellier is staying in, the names of the production crew for France can be seen: assistant director Louis Pitzele, chief grip René Strasser and set designer Willy Holt.
Edward Fox was cast as the Jackal after director Fred Zinnemann was impressed with him in The Go-Between (1971). Fox said that it was a line in the film, "Nothing is ever a lady's fault." caught his attention. When Zinnemann met him for the first time, Fox recalled that his exact words were, "Any actor who could make that line believable has got my ticket."
(at around 13 mins) Earlier in the film, Colbert exclaims how 960,000 Francs got stolen in three weeks by the OAS in a series of robberies. The scene was set on 6th July 1963, 3 weeks after the Jackal met the three OAS men. As in July 1963, the exchange rate between French Francs to the US Dollar was 4.9371:1, which when converted stands at $194,447, short of the $250,000 advance money to be paid to the Jackal.
Jean Martin plays Wolenski, one of the group of French military veterans (at least some of whom served in Algeria), who felt betrayed by De Gaulle's perceived capitulation to the violent tactics of the FLN, in support of the rebellion toward independence in Algeria. In the 1966 movie "The Battle of Algiers", Jean Martin plays Colonel Mathieu, a French Colonel of Paratroopers who arrives in Algiers to take control of the French military operation in Algiers, in an effort to take control of the city and of the violent rebellion toward independence.
(at around 1h 14 mins) When the British find the bogus passport request it's mentioned that it was applied for on July 14. That is Bastille Day, a national holiday in France that commemorates the storming of the French prison the Bastille (which signified the start of the French Revolution the end of the Monarchy in France).
During the shooting of the film, the author of the novel, Frederic Forsyth, introduced Edward Fox to an actual hired killer whom he had known when he was a war reporter in Africa, in the sixties, among mercenaries.
This was Fred Zinneman's first movie in 7 years. Zinneman, who had twice won the Oscar for Best Director, had seen a project called "Man's Fate", which had spent 3 years in pre production, cancelled just one week before filming was scheduled to begin. His next production, an adaptation of Alexander Solzhenitzen's "First Circle", was also cancelled at an early stage.
(at around 1h 30 mins) Michael Lonsdale (Commissioner Lebel) and Delphine Seyrig (Colette Montpellier) only share one scene together, when Lebel interrogates her in her home. Two years after making this film, the two actors portrayed a married couple in the film India Song (1975).
The character Denice, portrayed by Olga Georges-Picot, is an OAS mole whose discovery causes the official from the Elysee Palace to commit suicide. Olga Georges-Picot herself, a depression sufferer, took her own life during one of her bouts with the illness by leaping from a building in Paris.
In this film Michael Lonsdale plays a secret agent trying to thwart a British assassin in a high vantage point armed with a sniper rifle. In Moonraker (1979) he will attempt to kill British secret agent James Bond in exactly the same manner.
The trivia items below may give away important plot points.
The novel and film adaptation of "The Day of the Jackal" caused the London Public Records and Passport offices to tighten their regulations to reduce the chance of anybody's stealing and using a deceased person's identity, as the Jackal did.
A real-life forger told Frederick Forsyth three possible ways a person can obtain a false identity: apply in false name, steal another man's identity, or bribe an official for an "en blanc" passport and fill in the details. In the film, the Jackal uses all three, but the first was the most effective as it was very straightforward and very simple.
A scene was filmed where the Jackal shoots the Gunsmith with his custom-made gun (right after the Jackal asks for one explosive bullet from the Gunsmith). This scene was cut so that it would lead smoothly into the Jackal's rifle test in the forest, as well as provide a more interesting dynamic with the previous scenes of the Forger (who was trying to blackmail him and got his neck broken for it).