The men on the board of directors of Pepsi Cola are dressed in current (1981) suits, ties, and hairstyles in the showdown between them and Crawford. This scene would have taken place in 1959, so only Crawford is dressed correctly for the period.
When Joan brings Christina home from Chadwick school, she is wearing a hat, gloves and skirt all in the 50s style, which is correct. Her coat is an a-line design, boxy and shapeless, with a huge 70s pointed collar. This coat would not have been worn by Joan in the 50s as she was always wearing the very latest styles.
At the beginning of the birthday party scene, Joan can obviously be seen riding the Carousel behind Christina. However, in a subsequent shot, she is no longer on the Carousel. In another shot soon thereafter, she suddenly appears on the Carousel behind Christina again.
Joan's assistant is lacing up the left ice skate when the production assistant knocks to say they're ready for her. You can clearly see Joan's right foot is bare. She says, "Let's go," and gets out of her chair with only one skate on.
When young Christina fixes Mommie Dearest a drink when one of the "uncles" is visiting, the glass is half full of ice when she pours the alcohol. By the time she brings the drink into the room all the ice is gone.
When Joan walks into Mayer's office (only to be sacked) she is greeted by the secretary with "good morning". However, in a preceding scene, we hear Christina talking to her dolls about her mother having to see Mr Mayer "this afternoon".
In the bathroom cleaning scene, Joan has two rags in her hand. She pitches one to the floor, which Tina clearly does not pick up. Then Joan leans down to scrub the floor, and suddenly Christina has a rag in her hand.
Joan is reclining on a chaise lounge near the pool and Gregg sits down next to her. As the camera cuts between Joan's face and Gregg's face, Joan clearly changes position. Sometimes she's facing forward, sometimes she's gazing up into Gregg's face.
Carol-Ann seems to suddenly drop right out of the sky to oversee the pool race between Joan and Christina. You can briefly glimpse her while Joan and Gregg are having their previous discussion, over Gregg's shoulder when he says "Who calls, I run?", but in other shots she clearly isn't there.
When Joan and her staff are scrubbing the floor with cleanser she is wearing white sock and white "Joan Crawford" shoes. She wouldn't have worn shoes with black soles while scrubbing, especially since just moments later, she asks Greg to take his off.
During opening sequence set in late Thirties, a sightseeing tour bus drives past with an illustration of the famous Hollywood sign on its side. In reality, at that time the sign would have read "HOLLYWOODLAND" - the "LAND" portion of sign (which originally promoted a housing development called HOLLYWOODLAND) was not removed until the late 1940s.
When Joan meets with Mayer in his office, she is standing in front of a large portrait featuring a group of MGM stars. This scene is supposed to be taking place circa 1943. The portrait clearly features Esther Williams standing at the end of the front row in her Roman costume for JUPITER'S DARLING, which was filmed in 1955, 12 years after Joan left Metro.
When Joan Crawford substitutes for her daughter on a soap opera, producer of show gives her a pep talk during a commercial, indicating it was a live broadcast. In reality 'The Secret Storm' was taped and director later said Crawford's performance was so poor he had to patch it together in editing room.
Although it was recorded, The Secret Storm was "live tape", meaning that it was treated as if it were a live broadcast. At the end of each act, the actors stopped for the exact length of the commercials and then resumed taping.
The "wire hanger" scene has become the pivotal, and almost iconic, symbol of the movie, yet one must wonder where little Christina would have gotten the hanger to begin with. She was obviously too young to be picking up cleaning, so the hanger must have been brought into the house by a servant- so Joan's anger at finding the dress on the hanger was completely misdirected. One would think that Crawford would have issued a directive to her house staff to immediately remove any clothing from such hangers and to dispose of them.