Shelley Duvall's skirt getting stuck in the car door was initially accidental. Robert Altman found it amusing and asked her to intentionally do it throughout the rest of the filming.
The girls who played the twins were not professional actors. Robert Altman cast them after spotting both of them as waitresses in California.
Robert Altman had a believer in the head of production at 20th Century Fox, Alan Ladd Jr.. He felt that he could indulge Altman's offbeat projects, while the studio's more commercial films like Star Wars: Episode IV - A New Hope (1977) would make up for any financial loss. Peter Biskind, author of "Easy Riders," reports in his book that Altman and Tommy Thompson were driving to the airport, when Altman said, "Let's stop at 20th. I had a dream last night, I want to sell it to Laddie. Keep the engine running, it'll only take a minute." Altman darted into Ladd's office, made a deal for "3 Women," and was back in the car in time to make his flight.