In Barry Williams' autobiography, Growing Up Brady, prior to this episode, the show apparently hadn't been faring too well in the ratings and perhaps was even being considered for cancellation. This episode won its timeslot, the first to do so, and — as Williams went on — finally proved to be the boost the series needed ratings-wise. The show was on its way to becoming a TV legend.
Crappy Holidays: Carol's fallen ill with laryngitis, and everyone was looking forward to her solo of "O Come All Ye Faithful" in church on Christmas Day, and Christmas just won't be the same ... much less even worth celebrating if she's not well in time for her big performance.
Everyone Is Christian at Christmas: Although they Bradys are implied to be Christian (presumably of an unstated Protestant faith), this is the only episode where the family is seen in church. Not unlike every other sitcom before or after.
Lost Voice Plot: The episode revolves around Carol coming down with laryngitis, which threatens to prevent her from singing at the Christmas Day church service.
Maybe Magic, Maybe Mundane: Whether a miracle or coincidence, Cindy's wish for her mother to regain her voice on Christmas Day comes true.