Writer Paddy Chayefsky performed a number of roles on the film. Chayefsky was the writer and a producer and also narrated the film at the start. Chayefsky reportedly had full control over content and casting of the movie.
To avoid any interruptions to the day-to-day running of Metropolitan Hospital's vital services to patients, for interiors, the production took over two floors of a new psychiatric pavilion which were under construction and were not due to start receiving patients until January 1972 after principal photography had been completed.
The movie became a benchmark template for black comedies examining other institutions such as Network (1976) (the media) and Teachers (1984) (education), the first also being written by this movie's writer Paddy Chayefsky and the latter also being directed by this film's director Arthur Hiller.
Barbara Drummond (Diana Rigg)'s English voice is explained in this New York-set film's storyline as being attributed to being a Vassar College accent. This educational institution is described by that campus' website as being "a highly selective, residential, liberal arts college located in the heart of the Hudson Valley in New York State".