Other mistake: The scenery in the "I Love Lucy" on-stage scenes shows the Ricardos' apartment with a living room window. That was the apartment they moved into after Little Ricky was born. Before that, they lived in an apartment with no (visible) window in the living room.
Being the Ricardos (2021)
1 other mistake
Directed by: Aaron Sorkin
Starring: Nicole Kidman, Javier Bardem, Jake Lacy
Continuity mistake: Vivian is trying on a red dress in her dressing room when Lucille comes in to talk to her. Throughout the scene as the shots switch back and forth, the dress goes from being pulled up on Vivian's right shoulder, to off the shoulder part way down her arm.
Desi Arnaz: We've been through worse than this.
Lucille Ball: We have?
Desi Arnaz: No.