Continuity mistake: In Ziggy's first appearance in the series (S2, EP. 16 "Born to Be Wild"), he says he has two kids. He states "I had to make mine I checked them at birth, they're boys!" However in his second appearance in the series here, he states they were his girlfriend, Jill's, kids and the kids are back living with their father.
Continuity mistake: When Roseanne & Jackie talk about Arnie, they act like they haven't known him long. Jackie even states, "I don't know him." Yet, in episode "Why Jackie Becomes a Trucker," Jackie sleeps with Arnie. Roseanne says all the girls made a pact in high school that none of them would ever sleep with him.
Revealing mistake: Shortly after the fight with Becky, Roseanne asks Jackie to go across the street to get her something to drink, so she can smoke in secret. After Roseanne lights the cigarette and walks near the register, Jackie's plaid coat can be seen in the door's window as she waits for the next scene.
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.
Plot hole: All the kids and Arnie are about to play a basketball game. Darlene and Chuck Jr. battle in Rock, Paper, Scissors to see who picks first. They both throw scissors, and then Chuck Jr. says he gets to pick first. They should have done it over, since that would be considered 'a tie', he really didn't win. (00:12:10)
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: During the show's first two seasons, we are told Roseanne had a more slender figure during her younger years and didn't start gaining weight until after she began having kids. Later in the Halloween episode, "The Ghost of Halloween Past," Roseanne is shown her past, and her younger versions are not slender.
Factual error: When Becky locks Roseanne out of her bedroom, Roseanne heads to the garage for a screwdriver to take the door off the hinges - an impossibility since the hinges are on Becky's side of the door. In the next scene, the door is off the hinges.
Revealing mistake: When Dan calls Becky, there is a shot of her and Mark in their Minneapolis apartment. This is the exact same set that is used later for Darlene's Chicago apartment when she goes to college. The fireplace shape and style, the wallpaper, position of the bathroom door, and the windows are exactly the same. The only difference is that the Darlene version looks shabbier.