Debra Winger behaved erratically on the set because she was fighting severe cocaine addiction. At one point, she and Shirley MacLaine got into a shoving match.
Shirley MacLaine said Jack Nicholson would do crazy things on the set like show up practically naked, and that a lot of their scenes were improvised.
At the end of production, to congratulate him for completing his first movie, James L. Brooks received a book of "Life in Hell" cartoons, drawn by Matt Groening. Brooks was so impressed that he asked Groening to create cartoon shorts for The Tracey Ullman Show (1987), which led to The Simpsons (1989).
John Lithgow was called in to replace another actor. His part was filmed in three days, during a break from filming Footloose (1984).
Shirley MacLaine and Debra Winger were both nominated for 1983's Best Actress Oscar, which went to MacLaine. On her way to the podium, she reportedly whispered to Winger, "Half of this belongs to you," to which Winger reportedly replied, "I'll take half."