So when filming a pivotal scene in “Network” (1976), in which his character, an executive, summarily fires the news chief played by William Holden, Duvall drew on his own experience of threatening to throw someone out. A producer on the movie, he told Colbert, had come to his dressing room to give him a note. “I didn’t like the guy,” Duvall explained, “and I said, ‘Would you turn around and walk out of this room?’” with an expletive added for good measure.