Jane Fonda's Best Actress Oscar acceptance speech for this movie was one of the shortest in movie history: "Thank you...thank you very much members of the Academy and thank all of you who applauded. There's a great deal to say and I'm not going to say it tonight, I would just like to really thank you very much."
According to her autobiography, Jane Fonda hung out with call girls and pimps for a week before beginning this film in order to prepare for her role. When none of the pimps offered to "represent" her, she became convinced she wasn't desirable enough to play a prostitute and urged the director to replace her with friend Faye Dunaway.
Bree's apartment was built on a sound stage at a New York film studio where Jane Fonda could spend the night. The director even had a working toilet installed in the bathroom of the set. Jane contributed to decorating the apartment by deciding Bree would be a romance reader and have a cat. Jane remembered an actress from Lee Strasberg's private class that occasionally serviced John F. Kennedy, so she decided Bree had done this as well. A signed photo of Kennedy appears on the fridge in Bree's apartment.
The scene with the psychiatrist was mostly ad-libbed. Pakula used just one camera and later said he should have used two as Vivian Nathan's reactions were much more interesting in the takes where the camera focused on Jane Fonda.
In the original script Bree's psychiatrist was male but Fonda felt in rehearsals, that the character would never open up to a man so she requested that the part be changed to a woman. Fonda requested to shoot the scenes with the shrink at the end of shooting so she would have already fully internalized the character of Bree.
According to Donald Sutherland, the time the lightning took up was immense. The actors rehearsed usually from 7 to 9 AM, then returning to their trailers and usually waiting for noon or 1 PM before shooting started.
Warner Bros. wanted to remove both Jane Fonda and Alan J. Pakula from the project at one time before shooting started, but it did not work out as most people turned the studio down and so they came back to their decision.
The trivia items below may give away important plot points.
Jane Fonda said that she had to throw up while preparing for the scene where Bree goes through photos of dead prostitutes to identify her friends. She actually had gone to the city morgue too and it came as a great shock.
Although Fonda had planned on playing scared for the scene with the murderer (played by Charles Cioffi), when she heard the tape recording of the call girl about to be murdered and the fear in her voice, she unexpectedly started crying.