When Jean-Pierre Melville brought a copy of the script to Alain Delon, Delon asked him what the title was. When he was told the title was Le Samourai, Delon had Melville follow him to his bedroom, where there was only a leather couch and a samurai blade hanging on the wall.
Melville worried how he was going to shoot the scene where Jef drives the stolen car right into the scrap garage. Without missing a beat, Delon drove the car down the narrow alley and into the garage in one shot.
According to Rui Nogueira (author of the book "Melville on Melville" published in 1976), the caged bird shown as Jef Costello's pet in "Le Samourai" was the only casualty of the fire that destroyed Melville's studio in 1967.
The caged bird is a bullfinch (Pyrrhula pyrrhula). In the book "Melville on Melville" the director stated: "I wanted the opening shots to be predominately gray, so I used a female bullfinch because it is just black and white, without the male's orange breast."
The epigraph, credited to the Book of Bushido, was in fact written by director Jean-Pierre Melville. In his book "27 Movies from the Dark Side" Roger Ebert expressed disappointment at learning the quotation was fictional. Melville also wrote the epigraph in Le Cercle Rouge (1970), credited to Buddha.