All of the "moonrunner" cars in the film had actually been used by moonshiners in the Asheville, North Carolina, area, where the film was shot. The moonshiners sold the cars to the film company in order to buy newer and faster cars.
The role of Robin was offered to Elvis Presley, who was very interested, but the idea was nixed by Presley's manager, "Colonel" Tom Parker, who demanded more money for Presley's services than the producers were willing to spend.
The 1950 Ford that Robert Mitchum drives in the beginning is actually a 1951 Ford with a 1950 grille, and the chrome windsplits removed. The give-away: the V-8 emblems, the "Ford Custom" emblems on the front fenders, the dashboard, and steering wheel.