The cutaway Philadelphia joke is in loving memory of W. C. Fields. Fields, one of the great comedians of the 1920s and '30s, often insulted Philadelphia, his home town. In a 1927 Vanity Fair interview he proposed for his own epitaph, "Here lies W. C. Fields. I would rather be living in Philadelphia."
Nat Faxon voices the water park employee who gives Peter a "starburst." Faxon played a water park employee in the movie The Way Way Back (2013), which he co-wrote and co-directed with Jim Rash.
The title is a reference to the phrase "dearly departed".
Joe and Bonnie aren't in this episode