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.
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).