Continuity mistake: When Mommie is cutting Christina's hair it keeps on changing from long to short several times.
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.
Visible crew/equipment: In the hospital room, the nurse turns on the television to see Joan replace Christina in her soap opera, we see the crew in the reflection of the blank screen. We also see them when the nurse turns the TV off.
Other mistake: When Mommie is beating Christina with the wire coat hanger, the padding on Christina's back is visible, and you can tell by the motion of "Mommie's" arm, that she is not using any force.
Factual error: About 28 minutes into the film there is a scene where Joan walks into Christina's room and on the floor is a Knickerbocker Raggedy Andy doll. This version of the doll came out in the mid-1960's, yet the film takes place 20 years earlier.
Continuity mistake: Before Joan discovers the wire hanger, she goes through a group of blue clothes (Christopher's) and then turns to Christina's pink clothes. However, when she is yelling, we see that there are now pink clothes on both sides, with no blue in the closet. She then begins to throw the clothes off their hangers, and Christopher's clothes are back.
Continuity mistake: When Christina sees her baby dolls are missing she goes into Mommie's room. When she first walks in you see Mommie rolling up her sleeves in the mirror's reflection, but in Mommie's face-on shot, her sleeves are rolled down, which she then rolls up and puts cream on her elbows.
Continuity mistake: When Joan Crawford insists the bathroom isn't clean, she throws a rag on the floor for Christina to use and is then seen holding both rags while sprinkling Old Dutch Cleaner on the floor. In the close up of the same action, Christina has produced one of the rags from her right hand.