OK, just finished ep 20 and I'm a little confused...during the first show when the Conners won the lottery, wasn't there an episode where they paid off the mortgage? Roseanne put a little grill in the living room and gave Dan lighter fluid and a lighter so that they could burn the mortgage? Did I miss something somewhere?
Yes, they did pay off the house, and Roseanne and Dan did do that little celebration, but I think they don't care about the inaccuracies, similarly to how Dan came back to life.
In the final episode of the original season, we found out that the whole series was Roseanne writing her book, and some stuff, including them winning the lottery, never happened. So the house was not actually paid off in the original series. It was just something Roseanne wrote in her book.
However, they also said that Dan didn't really survive his heart attack in the original series, so there are some inconsistencies there as well. Many fans just choose to ignore the final season anyway because it wasn't good.