And of course the night phone call was a dramatic fabrication, though I thought, based on what I've read about Nixon, was a pretty logical leap as to the viewpoint Nixon had
In fact, Nixon was
known to made late-night drunken calls. These were to White House staffers though, or so I understand.
Anyway, the film's depiction of Nixon I thought was generally very solid. Langella got under his skin and he was very well written - it's pretty much on that basis I enjoyed the film as much as I did.
The scene makes sense as drama - they want to incorporate a more unhinged and less formal Nixon into the film for a scene, which makes sense, but at the same time make it a cathartic moment for the movie (which means he must be talking to Frost and at a key moment, as he is.) Screenwriting 101 maybe, but a wise call.