Filmed amid the ongoing Watergate political scandal, Robert Redford initially wanted the film to focus on the blacklisting of actors and writers during the McCarthy era. He was unhappy with cuts made to the film following a preview. "I think we'd both have preferred a more political Dalton Trumbo-type script," Redford recalled, "but finally Sydney came down on the side of the love story. He said, 'This is first and foremost a love affair,' and we conceded that. We trusted his instincts, and he was right."
Despite creative differences throughout filming, Barbra Streisand and Robert Redford worked well together. Although opposites in many ways, they used these differences to explore their respective characterizations of Katie Morosky and Hubbell Gardiner. According to screenwriter Arthur Laurents, the two actors often discussed their characters and their relationship with him. Laurents did not reveal to them that he based Morosky and Gardiner on the homosexual relationship between himself and his partner Farley Granger.
Barbra Streisand and Robert Redford had different approaches to acting. Streisand preferred to rehearse a great deal, while Redford preferred a spontaneous performance. "Barbra would call me up every night at nine, ten o'clock and talk about the next day's work for an hour, two hours on the phone," director Sydney Pollack recalled. "Then she'd get in there and start to talk, and Bob would want to do it. And Bob felt the more the talk went, the staler he got. She would feel like he was rushing her. The more we rehearsed, she would begin to go uphill, and he would peak and go downhill. So I was like a jockey trying to figure out when to roll the camera and get them to coincide."
In the original cut, film segments exploring Joseph McCarthy's Communist witch hunts amid the Second Red Scare (1947-1959) had much more screen time. However, director Sydney Pollack cut these segments to focus on the romance. The chief victims of the cuts were the storylines of Paula Reisner (Viveca Lindfors) and Brooks Carpenter (Murray Hamilton).
When Barbra Streisand heard the titular song for the first time, she made two important suggestions that transformed the song. She suggested a slight shift in the melody to send it soaring at a crucial point in the song, and she also suggested changing the first line of the song from "Daydreams light the corners of my mind" to "Memories light the corners of my mind."