Other mistake: Throughout the movie, Fred MacMurray wears his wedding band, even though it's mentioned several times that he is single.
Other mistake: The house appears to have three floors but the bathroom, the little girl's room, Grandpa's room (down the hall from bathroom and across hall from Rose and Esther) and Rose and Esther's rooms are all on the same floor at the top of the stairs. And exterior front of house shots show large windows on what would be a "second" floor that has no access from the main staircase.
Other mistake: During one scene where Bugs Bunny is barbecuing his carrot on a skewer near the fireplace, the carrot incorrectly appears behind the flames of the fire.