According to Jeff Bridges, Toshirô Mifune didn't know any English and had to learn his lines phonetically.
Reportedly, Richard Boone was drunk most of the time during his days on this movie. According to writer and director William Richert, Boone was so drunk throughout the shoot that Richert was quite impressed with how functional the man was. Production designer Robert F. Boyle worked with Boone once before on John Wayne's last movie, Il pistolero (1976), and he confirms in the documentary Who Killed 'Winter Kills'? (2003) that Boone was always drunk, but quite functional on that shoot as well.
This movie was co-financed by two alleged marijuana dealers, Leonard J. Goldberg and Robert Sterling. Sterling was sentenced to 40 years for marijuana smuggling while Goldberg, 16 days before this movie premiered on May 11, 1979, was found handcuffed and shot dead in his New York City apartment, allegedly a hit by mobsters for Goldberg's debt payment failure, on April 25 that year.
Belinda Bauer claims in the documentary Who Killed 'Winter Kills'? (2003) that this was the first movie in movie history to file for bankruptcy.
This movie was re-released in 1983 by writer and director William Richert's own company, four years after its initial release, with its deleted scenes returned, having been cut by the previous company.