Factual error: When Christina mixes a drink for one of Mommie's "guests" she bends down behind the bar to put a bottle back. Sitting on top of the bar is a Trigger Sprayer bottle of "Fantastick" - a spray that did not come out until the late 60's.
Other mistake: When Joan is cutting up her rose garden, she is ranting and raving about how mad she is at Mayer, and how they're calling her box office poison. But if you look closely at her lips, they aren't moving.
Trivia: During the rosebush/tree chopping scene, Faye Dunaway is chopping the tree, except when you see the close up. During the close up (when the tree falls), it is actually the films director Frank Perry chopping the tree.
Joan Crawford: Why can't you give me the respect that I'm entitled to? Why can't you treat me like I would be treated by any stranger on the street? Christina Crawford: Because I am not one of your fans!