There was indeed a disc jockey named Adrian Cronauer who worked for Armed Forces Radio in Saigon during the early years of the Vietnam War. Aside from that fact, this film pretty much deviates from reality from that point forward. If it happens in Good Morning, Vietnam, you be be pretty sure that it didn’t happen to the real Cronauer. This is really the story of what would have happened if you had somehow plunked Robin Williams back in 1965 Vietnam and set him to work for the military radio network.
That’s not to say it’s a bad movie. In fact, it’s the best movie on the pure comic side of William’s filmography, specifically because the role of this DJ perfectly matches the comedian’s unbridled improvisational humor.