When all of the ladies are sharing Sophia's bed because there's been a cold snap and she has an electric blanket, Blanche mentions that her bed has never been so cold on a Saturday night. A few minutes later, Dorothy - upset that the other ladies are keeping her awake - states that she has to get up for work "very early in the morning." Dorothy is a substitute teacher, and would not have to be up for work early on a Sunday morning.
The exclamation point carving on the back of the front door was carved by Bea Arthur the first day on set. It can be seen throughout the show's entire seven seasons.