The film I’m referencing is the Ninth Configuration. It’s one of my favourite films, a bit like Apocalypse Now meets One Flew Over The Cuckoo’s Nest.
It’s about a psychiatric hospital for soldiers during the Vietnam war. It’s set during the end where most people thought the war was unwinnable. The suspicion was that many patients were faking it.
One day a new psychiatrist joins and he allows the patients to indulge their fantasies. In this scene the patients had said they wanted to play escape from Colditz so they wanted the personnel dressed up as Nazis.
It’s a very good film, incredibly funny to begin with then half way through it flips and becomes deadly serious.