This is the only episode with a hint of Christmas, although the school program is called a Holiday Festival. There is no true Christmas Episode in the entire series.
At about the four-minute mark, June closes her finger in the refrigerator door. She plays it off pretty well, but she can be seen rubbing it as the scene continues.
When Wally finishes Beaver's haircut and steps aside to reveal the disastrous result, there is an 18-second period of dialog-free canned laughter, possibly the longest such instance in the entire series.