Nat 'King' Cole had a nightly singing engagement at a Lake Tahoe nightclub. He would commute daily between Lake Tahoe and the set in order to do both. Everyone noticed that Cole was coughing a great deal whenever he was on the set and losing weight, but most figured he was just running himself down with such a gruelling schedule. Unbeknownst to them and to Cole himself, he was already very sick with lung cancer.
At his acceptance of the Oscar, Lee Marvin opened by saying, "Half of this probably belongs to a horse out in the Valley somewhere".
Lee Marvin earned just $30,000 for his work here. Following his Oscar win, he was earning up to $1,000,000 for Paint Your Wagon (1969) and Monte Walsh (1970).
Modern-day audiences regard Lee Marvin's Oscar win for a raucous comedy with puzzlement, especially given the heavy-hitting dramas released the same year, such as Darling (1965), Doctor Zhivago (1965), and Ship of Fools (1965). At the time, however, Marvin's over-the-top portrayal of two total-opposite brothers was a revelation following a career playing one-note heavies. The actor had never had an opportunity to show his lighter side, and audiences loved what they saw - to the point where Marvin's nomination that year was for this movie rather than the far more prestigious and dramatic aforementioned Ship of Fools.