Patty Duke writes that she fought with director Fred Coe on the set, due to a manic depressive episode. She fiercely challenged the ending with Natalie remaining independent, saying, "It may not have been as noble, but there's no way she was going to give up that man. It might have made a more successful picture had they stayed together, but by then nobody was interested in what I thought the ending should be."
Frequently missed shot: Mom tells Patty Duke's character it'd be nice if she came over for dinner, cooked a chicken (i.e., wants her to be more 'normal'). Her response is that it'll be a cold day in hell before she's so conventional. In the final shot of the film, Patty is riding a motor scooter in downtown New York, going to visit her mom, hoping to reconcile. There's a plucked chicken in the basket on the back of the scooter.