It took Richard Nixon getting ahold of him personally -- in the middle of the night -- for him to finally get up and do some real research himself (at least in the film -- which was probably dramatized for effect).
Yep, that scene didn't happen in real life. I recall reading there being other fabrications in the film to make it more dramatic - off the top of my head, Frost's female interest in the film didn't exist.
But yeah, that was a very good film. Langella was wonderful as Richard Nixon.