Miles Davis recorded the music with a quartet of French and US musicians in a few hours (from 11pm to 5am one night), improvising each number and allegedly sipping champagne with Jeanne Moreau and Louis Malle.
Louis Malle shot his lead actress Jeanne Moreau in close-up and natural light and often without make-up. Moreau, an icon of French film, had never been seen like this before, to the extent that lab technicians, reportedly appalled at how unflatteringly she was photographed, refused to process the film. Once they were persuaded to, however, it soon began clear that Malle had captured every nuance of Moreau's performance.
Mercedes-Benz "Gullwing" 300SLs are highly sought-after collector cars now. Produced from 1954 to 1957, they originally sold for $11,000 USD. A pair (Gullwing and Roadster) were offered together for $1.3 million USD in 2009, and in 2012 an extremely rare 1955 model with aluminum body (of which only 29 were made) was sold for $4.62 million USD.
The German tourists' Mercedes-Benz 300SL W198 "Gullwing" was the fastest production car of its day. It is the first production car with direct fuel injection, which is why the characters mention that the engine has no carburetors.
Julien's car is a 1952 Chevrolet Styleline Convertible with the registration number 837 BK 75. The funny "egg" that's parking in front of the flower-shop when Julien is running outside after being released from the lift is a German "Heinkel Kabine", a three-wheeled rolling cabin produced from 1956 to 58. It had two seats and was entered from the front by a single door. With 9,2 or 10 HP it made up to 90 km/h after all.