Visible crew/equipment: When Bev hears "movement" on the baby monitor everyone rushes toward Roseanne on the stairs, and just as Roseanne comments that they're all "scary enough individually," we can see the second camera appear at the left side of the screen. Then when Bev walks through the bedroom's doorway, we can see movement of the boom mic at the top left corner of the screen, and when DJ turns on the camcorder we can see the end of the set from the POV of the camcorder.
Revealing mistake: When the family is eating the Christmas cookies, look at the top of the screen. In the kitchen, you can blatantly see where the top of the kitchen actually ends, revealing gray panels. The Conner's ceiling never went up this high, so it is definitely set material.
Continuity mistake: When a depressed Roseanne emerges from her bedroom after Dan has left her, she tells Nancy and Leon that she wants to turn over her and Jackie's shares of the restaurant to them. She says she wants Nancy and Leon to experience the same sense of accomplishment that she and Jackie felt when they first opened the business. However, Roseanne seems to have forgotten that it was Nancy, along with her, Jackie, and Bev, who started the restaurant.
Continuity mistake: In the episode Terms of Estrangement Part 1, Roseanne goes for an interview at "The old Wellman Factory" which was closed down and turning into a printing press. Then, in the episode Lanford's Elite, Roseanne and Jackie team up with Edgar Wellman Jr. to try to save the factory from shutting down by paying off past due debts and making all the current employees part owners.