Robin Williams worked overtime to create his character for Good Morning, Vietnam

During the limited time leading up to filming, Williams and his assistant (and future wife) Marsha Garces had to begin their research. Williams went to Thailand (Bangkok starred as Saigon in the film) and, through a historical consultant, began reading about soldiers' slang in Vietnam in 1965 and immersed himself in the pop culture of Thailand. era - avoiding the embarrassment of dropping an anachronistic TV reference. Williams wrote extensive notes on topics that would be banned: Kinks, Beatles, Top 40, psychedelic, etc. Williams also learned some pretty crude shorthand. "Ho Chi Minh's Revenge" was, for example, a US military term for diarrhea. Other nicknames the military boys had developed were even less couth.

Then, at night, he and Garces would return to their hotel room and learn Cronauer's vociferous monologues. This type of workshop and test material is more traditionally done during long tours and extended gigs at comedy clubs; most top comedians perfect their jokes and test their material for several months or even years before the taped special reaches an audience. Since there were no comedy clubs in Bangkok – and because time was tight – Williams simply tested her work on Garces. Garces essentially co-wrote Williams' rants in the film.

With plenty of material to draw from, Williams then had to play it. The Cronaur scenes in the cabin only make up about 12 minutes of screen time in the film, but they are the defining feature.