Plot hole: When the Jackal is stopped at the French border, he is sent to a room with dozens of blond guys who look like him. Despite this, he does not consequently act as if they are looking for him. As if he does not suspect the Police are looking for him, he goes into a hotel and checks in with his current name.
Character mistake: Towards the end of the film the Jackal, in disguise as the fictional one-legged, grey haired Frenchman Andre Martin, finishes setting up his sniper's nest and removes his beret, revealing that he has only dyed his hair grey where it protruded. He has a circular mop of his normal chestnut brown hair under his hat! This is an incredibly stupid thing to do - it is a perfectly normal thing for a policeman (or any other security operative) to ask that someone showing identity papers remove his hat if he is wearing one. The Jackal is a professional assassin who meticulously prepares for all contingencies - he isn't going to throw away his whole plan for the sake of a bit of extra hair dye. (02:10:05)
Plot hole: An important plot point (in the book and the film) is that Charles Calthrop - thought to be the Jackal, at that stage - played some mysterious part in the 1961 assassination of Rafael Trujillo, the dictator of The Dominican Republic, and rumours of his involvement came to the attention of MI6 and Special Branch, leading to the accidental exposure of the Jackal's false passport. In fact there is no mystery at all about the assassination of Trujillo and there were no shadowy foreigners involved. It was organised by Trujillo's own senior aides, amongst them General Juan Tomás Díaz, Antonio de la Maza, Amado Garcia Guerroro and General Antonio Imbert Barrera. The gunman was later identified as Luis Aniama Tio. All the conspirators except Tio were arrested, tortured, and shot. There was no panicked evacuation of foreigners who were involved with Trujillo's regime, and no reason for them to be concerned - the government did not fall and Trujillo's brother Hector took over as President, ruling in a brutal and totalitarian manner for a further eight years. Any rumours of a mysterious Englishman would have been dismissed out of hand and would not have made it onto even the lowest level filing system anywhere in Whitehall.
Plot hole: When the French conclude - incorrectly - that Charles Calthrop is the Jackal, they contact the British authorities and obtain his file photograph from the passport office. The photograph is of Edward Fox in character as the Jackal - but it shouldn't be! The Jackal and Calthrop have no connection. The Jackal never used his identity and did not apply for a false passport in his name. The photo should have been of Edward Hardwicke in character as Charles Calthrop, who appears in the closing minutes of the film. The two actors do not look anything like each other.
Other mistake: Interior Minister Roger Frey advises Commissioner Lebel that all members of the police, military and other security forces attending the ceremonies on the day the Jackal is expected to strike will be issued with lapel badges at the last moment, in case he is going to try to masquerade as one of them. We see hundreds of such people in the next part of the film, including Lebel himself and the CRS private who allows the heavily disguised Jackal through the barricades around the site of the ceremony DeGaulle is due to attend. Only the CRS private wears a lapel badge. Not one of the other police or military officers in attendance is wearing a lapel badge of any kind. (01:58:15)
Visible crew/equipment: The boom mike dips into shot above Jules Bernard's head just before the Jackal murders him. (01:56:25)
Factual error: When the Jackal is driving into France in his 1963-correct Alfa Romeo Giulietta, he passes a red Alfa Duetto. Those were not made until 1966. Likewise the Renault 12 or the electric locomotives.
Continuity mistake: When the Jackal is parking his car near the hotel, he parks in a small gap between two cars. When he gets out of his car, the leftmost car is gone.
Continuity mistake: At the beginning, just after the title credit the President's car is machine gunned and you see the back windshield shatter and disintegrate. Moments later the car arrives at the airport with the windshield intact. We see de Gaulle get out of the car with the intact rear windscreen.
Revealing mistake: When the Jackal is shot at the end of the film, he's thrown back against the wall of the room which moves, revealing it to be a wooden set. Additionally, the hole in the wall with the stunt cable can be seen in slow motion.
Continuity mistake: When the Jackal assembles the gun, to shoot the President, he puts the pieces on the table. Next shot the table is clear as he puts a chair on top to steady the gun.
Factual error: Charles de Gaulle's Citroen DS19, a vehicle that appears repeatedly, is an anachronism: it's a 1965 model used in a movie set in 1963. Although the design differences are few, they are noticeable from the outside. It's difficult to imagine why the production team used an incorrect car that got so much screen time (as opposed to the aforementioned 1966 Alfa and several other background vehicles).
Continuity mistake: The first time we see the beautiful Alfa Romeo Spider, the registration plate at the end of the car says GE1761, without a space between GE and 17. The next time we see the car, when he practices shooting in the the woods, the plate says GE 1761 with a huge space between GE and 17.