This episode of M*A*S*H was almost entirely improvised
"The Interview" featured each actor at the top of their game.
Trusting your actor is one thing, but trusting them to make up their lines is another completely. While the greatest thespians can always deliver believable snippets of story, it takes a rare breed to commit and stay in character enough to improvise lines that haven't been written for them ahead of time.
While lots of shows in the '70s and '80s were filled with great actors, M*A*S*H held the distinction of putting together perhaps the strongest ensemble ever on television. The lengths the cast went to for audiences to suspend their disbelief made for a show that continues to resonate today. They were all so believably a military unit that it's hard to remember they never actually served together.
The M*A*S*H cast was so locked in as their characters that they were able to nearly improvise a full episode in the show's fourth season. Titled "The Interview," the episode sees real-life journalist Clete Roberts join the 4077th for a day-in-the-life style report. To further the facsimile of a 1950s newsreel, the proceedings were filmed entirely in black and white. But that wasn't the only measure the creative team took to make that particular hour seem realistic.
According to the Fox television special M*A*S*H: The Comedy That Changed Television, the actors made up much of their own dialogue for the episode's interview segments with Clete Roberts. While they were all surely gifted enough to believably deliver interview answers that were already written, the producers instead entrusted each actor to answer the questions in-character.
However, it was revealed that one of the most emotional beats was devised by series creator Larry Gelbart.
When Father Mulcahy tells Clete Roberts all about how the war has changed his life, actor William Christopher delivers lines that were planned out to give the monologue the gravity the moment deserved.
Regardless of the extent, the fact that a majority of the cast was capable of staying true to their characters in those off-the-cuff moments is truly a feat of TV magic.