Initially, the film company didn’t know how bad off Cazale was. The insurance folks wouldn’t back him, either (since they estimated he wouldn’t live to finish the film), but apparently DeNiro himself put up the $$ for his insurance and Meryl Streep (whom Cazale was engaged to) threatened to walk if the film company fired or replaced him. Cimino moved up to filming all of Cazale’s scenes early, so it was pretty much a group effort of getting behind him to make sure he was able to complete his work.
Just amazing. Yep...