When Mrs. Roper and Chrissy open the girl's bedroom door, there is clearly a wall right behind them and not an open space to the living room as there should be.
During the big argument between Chrissy and Janet, Jack is trying to help by talking to the girls as they go from room to room. As Chrissy goes into the bathroom John Ritter got too close to the door, when Chrissy slams it, it hits Ritter in the nose. The actor seems to be momentarily caught off guard by the incident.