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.
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.
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.