Blacklisted writer/director Abraham Polonsky wrote the original screenplay for the film. When Irwin Winkler decided to rewrite the script by changing De Niro's character from a Communist to a more generic Liberal, Polonsky had his name removed from the film's credits. "I wanted it to be about Communists because that's the way it really happened. ... They didn't need another story about a man who was falsely accused," he said in an interview in the New York Times.
Robert De Niro's character walks in front of a poster from the play 'A Tramway named Desire', an evident reference to its director Elia Kazan - a famous informer who denounced his friend director John Berry (the inspiration for De Niro's character).
In Irwin Winkler's rewrite of Abraham Polonsky's script, the David Merrill character was changed from a Communist Party member to a relatively apolitical liberal. Winkler based his conception of Merrill on blacklisted director John Berry, who played a nightclub owner in the Winkler-produced 'Round Midnight (1986). Ironically, Berry had been, like the original character written by Polonsky, a communist at the time of the Hollywood Red Scare.
When the di Niro character visits Zanuck watching dailies early on in the movie, we see that the dailies on screen are Marilyn singing a number from "Gentlemen Prefer Blonds" and Zanuck tells "Howard" (Hawks) the director (on the phone) that he can't see any difference in the various takes. GPB 1953 and the last scenes of GBS are Feb 1952.
There is a Milwaukee Braves baseball pennant on the wall of Merrill's son's room. This film takes place in 1951 and 1952. The Braves didn't move to Milwaukee from Boston until 1953.
Before going to London, Joe is seen editing the classic The Boy with the Green Hair, but the movie was already released in 1948 and Guilty by Suspicion story takes place in the 1950's.
Congressman Velde: I wanna know how many Communists you knew. I wanna know how many you know, how many you've worked with. I wanna know what your association is with them.
David Merrill: [about Dorothy Nolan]
She was a good wife, a good mother, and you're responsible for her death. She was falsely accused, she couldn't get work, her son was taken away from her - all because of this committee. In the name of ridding the world of Communism, you destroyed her life.