First production to use the new, more sensitive Eastman 4-X film, which eliminated the need for a lot of expensive lighting equipment, especially in nighttime scenes.
Production was temporarily delayed as reported in the 18 November 1964 edition of Daily Variety, after Ann-Margret accidentally struck director Ralph Nelson in the head with an ashtray she was supposed to throw at Alain Delon. The wound reportedly required nineteen stitches to close.
Eddie's car is a 1931 Ford Model A roadster, slightly modified and customized.
Ralph Nelson: As a motorcycle policeman and a closeup of feet near the end - according to an article in the 10 December 1964 edition of Daily Variety.