Robert Towne refused a chance to write the screenplay, despite a $175,000 salary, saying "I didn't want to be the unknown Hollywood screenwriter who fucked up a literary classic." Instead, he wrote Chinatown (1974), which earned him an Academy Award and established him as one of the greatest screenwriters of the period.
Mia Farrow writes that the main reason she couldn't create on-screen chemistry with Robert Redford was because of Redford's total absorption in the Watergate scandals that were rocking Washington, D.C. at the time. Farrow says Redford spent all his free time locked in his trailer, watching the political scandal unfold on television. Two years later, Redford played Watergate reporter Bob Woodward in All the President's Men (1976).
Natalie Wood was offered the role of Daisy, but she allegedly balked when the producers insisted on a screen test because the actress hadn't been in a movie for nearly 5 years (since Bob & Carol & Ted & Alice (1969)).