Alan Ruck (Connor) actually tore his rotator cuff in real life, so they wrote it into the episode.
According to Matthew MacFadyen, the line "Yeah? Prove it." was ad libbed by Nicholas Braun.
The title of this episode come from "The Berenstain Bears and Too Much Birthday" written by Stan Berenstain and Jan Berenstain and originally published in 1986. In the book, Sister Berenstain becomes overwhelmed by her birthday party, much like Kendall Roy.
The production worked with Meow Wolf, an immersive art installation company, to come up with some of the set pieces in Kendall's birthday.
According to the Instagram account Succession Fashion, Shiv Roy's green party outfit is a $1,790 stretch-jersey midi dress by Montse.