When Dr. Herbert Bock rants, "We have established the most enormous, medical...entity ever conceived and people are sicker than ever!" the slight pause, searching for the word "entity", was spontaneously ad-libbed by George C. Scott to save the take. The scripted line was, "we have ASSEMBLED the most enormous medical ESTABLISHMENT ever conceived." Scott heard his slip in mid-sentence, so he reworded the line so as to not make it repetitive. Director Arthur Hiller loved the save so much he used that take in the movie.
George C. Scott demanded a $300,000 salary to play Dr. Bock. Rod Steiger was offered the part, but when he asked for even more money, the producers cast Scott.
This movie became a benchmark template for black comedies examining other institutions. Network (1976) was written by screenwriter and producer Paddy Chayefsky. Teachers (1984) was directed by Arthur Hiller.
In addition to his role as Edmund Drummond, Barnard Hughes also played Dr. Mallory. This initially confused some audiences, who thought Drummond was pretending to be Mallory.