This is a fun example of how the marketing of movies was done in the decade I was born. Media sent the interviewees questions that they would ask, and the actor would give responses while being filmed in split-screen style; the interviewer would then splice their questions onto the other side of the screen, record it, and
voila! A live interview for their televised show.
George C. Scott and Peter Sellers chose to do their faux interview on set and in character. But you never know what you're going to get with Sellers...
(YouTube Link)
As if I needed another reason to love this film.