Halloween - The Final Chapter - S8-E5
Continuity mistake: Roseanne becomes pregnant at the beginning of Season 7, and it is before the Halloween and Thanksgiving episodes, so she is in her first trimester during the holidays. However, Roseanne does not give birth until the following year in the Season 8 Halloween episode. Her pregnancy has lasted for well over a year.
The Last Thursday in November - S8-E8
Other mistake: Roseanne gave birth to Jerry on October 31st. That Thanksgiving, on November 21st, Jerry was only 3 weeks old. However, he is side by side with Andy sitting in a high chair on his own, sitting straight up, holding his own head up.
Factual error: 1/4 through the show, Darlene, Becky, David and Becky's husband, Mark, are playing Scrabble. Mark puts down "oxygen" on the board in the lower corner with the "O" covering the triple word square. David is counting up the score and says the "X" is on the triple letter box, and totals the points up to 99. The problem is there is no triple letter box next to the triple word box or even on the outside edges of the board.
Construction Junction - S8-E16
Continuity mistake: Stumbling in the dark bedroom, Dan rips off one of the bedposts, and he is holding it, while Roseanne turns on the light. Then, in the next shot, suddenly it's back on the bed again. (00:07:30)
The Wedding - S8-E23
Character mistake: When Roseanne, Darlene, Jackie, Bev, Becky, and Nana Mary are dressing for Darlene's wedding, Nana Mary comments that all of them were pregnant when they married. However, Becky, was not pregnant when she and Mark eloped and they never had children together. Roseanne was not pregnant before marrying Dan. When the series began, Becky was 13 years old and Dan and Roseanne had been married 15 years.
Answer: Clearly, the only person who could truly answer this question would be a set designer for the series, or someone else directly connected to the series who would have this kind of detailed information. I looked on IMDb.com and Cheryl Lanner is credited as set designer through 1997. I quickly found her Facebook page, and I directed your question to her. After some time, Ms. Lanner has replied as follows: "I decorated the last season 1/2 but after 9 seasons the sofa just plain got worn out and had to be repaired from 8 years of usage. There was a board put on the sofa but as I've said, it was due to so much usage. If they had back problems I was unaware of them, but you can be assured that if that was the problem it would have been fixed immediately. Take care Michael!"
Michael Albert