In the limited time before filming, Williams and his trusted assistant (and future wife) Marsha Garces had to embark on research. Williams went to Thailand (Bangkok plays Saigon in the film) and asked a history consultant, started reading soldier slang in Vietnam in 1965 and immersed himself in the popular culture of the time. – avoid the embarrassment of abandonment. a reference to anachronistic television. Williams wrote down many notes on what topics to use: Kinks, Beatles, Top 40s, hallucinations, etc. Williams also learned some pretty complicated shorthand. For example, “Ho Chi Minh Revenge” is a US Army term for diarrhea. The other nicknames that army boys have developed are even less crude.
Later, at night, he and Garces would return to their hotel room and discuss Cronauer’s gripping monologues. This kind of test and measurement material is often done during long touring tours and extended gigs in comedy clubs; Most popular comedians hone their jokes and test material for months or even years before the specials are taped to audiences. Since there were no comedy clubs in Bangkok – and because times were running high – Williams was simply experimenting with his work on Garces. Garces is essentially the co-author of Williams’ quotes in the film.
With so much material to draw from, Williams then had to do it. The Cronaur scenes in the booth only take up about 12 minutes of the film’s screentime, but they’re its standout feature.
https://www.slashfilm.com/992834/robin-williams-worked-overtime-to-create-his-character-for-good-morning-vietnam/ Robin Williams worked overtime to create his personality for Good Morning, Vietnam