The names of the guests invited to the party (the Sedgwicks, the Orsattis, and the Buzzells) were taken from some of Desi and Lucy's real-life friends' names.
This episode aired on Christmas Eve of 1951. At the end of the episode there was a tag scene in which the four regulars are dressed as Santa Claus bringing presents into the Ricardo's apartment to put under their Christmas tree. The four have a hardy laugh that they all thought of the same idea to dress up as Santa and decided to sing Jingle Bells. During the song the foursome dance around the Christmas tree and when they come out in front of it they notice it's five of them not four. After the foursome pull of their beards to reveal themselves they turn to the fifth Santa and tug his beard. That Santa gives a yelp and then disappears into thin air. The foursome embrace each other and look at the camera wishing everybody a Merry Christmas. This act would be repeated in the season six Christmas episode in 1956. This tag was not rebroadcast for syndication.
This is the first time we see Lucy's famous crying routine. Ethel joins in for this first time.
Ricky and Fred are performing for the troops, because this episode was filmed during the Korean War.
It's clear that Fred and Ethel have an active sex life, based on Fred's reaction when he and Ricky deduce that all the knitting the women have been doing is because they're pregnant.