Warren Beatty hates casinos and gambling, he did this movie mainly as a favor to his mentor, director George Stevens.
Frank Sinatra was originally cast as Joe Grady, but dropped out due to concert commitments according to Kine Weekly on November 16, 1968. He was replaced by Warren Beatty.
Production was delayed two months because Elizabeth Taylor needed time to recover from a hysterectomy.
Because Dame Elizabeth Taylor wanted to be near husband Richard Burton, who was at the time filming Staircase (1969) in Europe, she demanded this movie, with its Las Vegas setting, be filmed in Paris, France. The studio agreed, thereby increasing the budget considerably as detailed American streetscapes, casinos, apartments, and supermarkets had to be re-created in Paris. In the end (after eighty-six days shooting in Paris) the company had to move to the real Las Vegas, Nevada anyway for ten additional days of intensive shooting.