Mark Felt did not choose Bob Woodward at random from the Washington Post's roster of reporters. Felt and Woodward had known each other for a few years with the two having initially met one another while Woodward was serving in the U.S. Navy as an Admiral's aide. In fact Woodward had sought out Felt's advice on his future when his discharge from the Navy was approaching.
Apparently much of Diane Lane's 'electric performance' was cut due to running time constraints. At a press conference director Peter Landesman and Liam Neeson both championed Lane's performance saying how devastated they all were (especially Lane herself) that so much of her superb performance was left on the cutting room floor. There were hints that these scenes may be included as 'deleted scenes' or as an 'extended cut' on the home video release of the film.
Following the passing of both of her parents, Joan Felt has become a spokeswoman/flame keeper on her father's behalf in televised retellings of the Watergate saga, including in the Emmy-nominated All the President's Men Revisited (2013), narrated by Robert Redford - who plays Bob Woodward in All the President's Men (1976) - and produced by Redford and his company Sundance Productions, and ABC's Truth and Lies: Watergate (2017), marking 45 years after the Watergate break-in. In the former, she also talks about how she learned that her father was Deep Throat after Woodward visited him at his house outside San Francisco 3 decades later.
Two of the most famous figures in the exposure of the Watergate scandal, Washington Post reporters Bob Woodward and Carl Bernstein, are not at all important characters in this movie (Woodward, played by Julian Morris, appears only briefly, and Bernstein doesn't appear at all).
Writer / director Peter Landesman told Time Magazine that this was a deliberate decision because he wanted to vary from the "prevailing Watergate narrative." Although Landesman did not mention this during his promotion of the film, his decision to omit any depiction of Bernstein may have also been influenced by the fact that Bernstein has in the past been notoriously difficult to deal with regarding his own portrayals in movies. In a March 2016 interview in Collider, Jacob Bernstein (a son of Carl Bernstein and Nora Ephron) said that the most challenging aspect of making Everything Is Copy, the 2015 documentary about Ephron, was the protracted negotiation with his own father about Bernstein's appearance in the film. And in that movie itself, Jacob Bernstein also says that his parents' divorce stretched on for years and was a great deal more complicated than most divorces in part because of his father's insistence on negotiating on the content of another movie, the film adaptation of Nora Ephron's roman a clef account of their breakup, Heartburn (in which Jack Nicholson played a thinly veiled version of Bernstein).
Felt revealed himself as Deep Throat in a 2005 article in Vanity Fair, where Carl Bernstein was a contributing editor. Once notified that the article would be published, Bernstein and Bob Woodward met with Ben Bradlee (their executive editor at the Washington Post, played by Jason Robards in All the President's Men (1976) and Tom Hanks in The Post (2017)), who advised them to confirm. Bradlee had been one of the few people that Woodward or Bernstein told the truth beforehand about Felt being Deep Throat.