"Escape (The Piña Colada Song)" by Rupert Holmes is playing at Kim and Glenn's cookout. In Nailed (2016), Jimmy and his film crew gain entry to an elementary school by convincing the principal that Holmes was an alumnus of the school.
According to AMC's Talking Saul, Vince Gilligan said that six years have passed from the dissolution of Saul and Kim's marriage to the present day.
The birthday card that Kim signs for her office mate is similar to the office birthday card that Mike is asked to sign when he does a drop-by security inspection at Madrigal in episode 4.1 (Smoke). The birthday cards are both cat themed and use the same pun, "purr-fect," in their punchlines. This is a way of illustrating the mundanity and uniformity of office culture.
Jimmy told Kim to put on a "hairshirt". A Hairshirt is a type of garment made from rough animal hair (usually that of goats) like an undershirt which pressed against the skin so the coarse hair will rub and scratch the wearer. It was especially used by monks in the Middle Ages, a type of mortification for committing a venial sin.
Rhea Seehorn (Kim) was absent from the series since "Fun and Games", three episodes prior. Gilligan mentioned that several people asked if Kim was deceased. While acknowledging it as a possibility, the writing staff never considered killing Kim. The writing team purposely chose to refrain from including Kim until the last episode, with Vince Gilligan and Peter Gould citing the primary rationale as being for "showmanship". Seehorn interpreted that "a part of her has died", and her overall character as being a "shell of a person". She discussed Kim's character with Gould and Gilligan, noting that while there was "nothing wrong with her life", it would be considered "tragic" as "we know what she could have been, and her potential and what she wanted".