 Michael Herr (qv), a very close friend of Stanley Kubrick (qv),  helped write much of the screenplay, particularly the part set in  Vietnam. His contributions to the script are based largely on his  own experiences as a reporter covering the war. Like Joker and  Rafterman he was essentially freelance and allowed to travel  anywhere in the country. Additionally, the scene where Joker and  Rafterman watch the crazed gunner in the chopper machine