James Dean was signed to play Billy the Kid in this picture but the role was given to Paul Newman after Dean's death. It was the second role Newman inherited from Dean (who had also been signed to star in Somebody Up There Likes Me).
Paul Newman was widely felt to be miscast as Billy the Kid since at 33 he was considerably older than the character.
Directorial debut of Arthur Penn.
First film for producer Fred Coe.
Interestingly, the title of this movie promotes a common misconception that was proved untrue in 1986. Two almost identical tintypes of Billy the Kid were taken at the same time in 1880. The original of one tintype disappeared years ago. The second original tintype was preserved for years in the Sam Diedrick family and came to light only in 1986. Since tintypes are reversed images, the picture from the first tintype led to the myth of the left-handed gun. After the second tintype came to light, the reversed image was reversed to show the Kid as he actually posed, with a Winchester carbine in the left hand and his holstered Colt single-action on his right hip. See Utley, Robert M., Billy the Kid, A Short and Violent Life, University of Nebraska Press, 1989. Statement following page 110 alongside the picture of Billy the Kid.
The sets for the town of Medaro were actually left over from Warners' 1939 epic Juarez. Although they were in state of great disrepair, parts of them were salvaged for use in "The Left-Handed Gun."