The phone conversation at midnight between Frost and Nixon never actually happened. Screenwriter Peter Morgan got the inspiration from well-known phone calls at midnight that Nixon did to some government members during Watergate.
Frank Langella admits that he usually enjoys playing cards and joking around on movie sets, but felt it would compromise his character if he didn't remain presidential on this set. While working on this movie other cast and crew referred to him as "Mr. President." Langella suggests almost none of the crew ever met Frank Langella.
In an article called 'Stopping the Rot' in The Sydney Morning Herald (Australia) on May 3, 2008, Ian Munro quoted James Reston Jr., Frost's Watergate adviser: 'I was in army intelligence ... and the Mutt and Jeff, good cop-bad cop thing is usually two people, but Frost, he did both roles.'
The Broadway production of "Frost/Nixon" by Peter Morgan opened at the Bernard B. Jacobs Theater in New York on April 22, 2007, ran for 137 performances and was nominated for the 2007 Tony Award for Best Play.
Oliver Platt previously played Yankees Owner George Steinbrenner in the ESPN mini series The Bronx Is Burning. In 1974, Steinbrenner was convicted and suspended from baseball due to illegal contributions made to Nixon's 1972 Re-Election Campaign.
The piano piece you can hear in the movie is the "Richard Nixon Piano Concerto #1", written by the President himself and is played by Frank Langella, who plays Nixon. A video footage of the actual Nixon, playing it on a TV-show, can be found on the net.
The pivotal scene where a drunken Nixon telephones Frost in the middle of the night (something that never took place in real life) was filmed in two adjacent sets with both actors on stage at the same time in order to bring a real sense of spontaneity to such a key scene.
Frank Langella stayed in character throughout the entire production. This naturally isolated him from most of the cast and crew who were overly deferential to him, something that the actor was pleased about as it was an essential component of his character. On the last day of the last shot, Langella dropped the facade and shouted to everybody "Hello, everyone, I'm Frank!"
To signify that the David Frost character never stopped working, Michael Sheen was dressed perpetually in suits. The one exception is at the start of the film before Frost latched onto the Nixon interview idea when he is seen topless in bed.