The Goat, Mr. Cool, is a real goat. His head is really moving, but his body is just a photo of his actual body, edited to look like it's moving.
Jessica McKenna, as Lennon, lends her singing voice to "The Goat Song," "City Day," the theme song, and "Close the Freezer, Open Your Heart," but she also sings on her podcast "Off Book: The Improvised Musical."
June Diane Raphael, who voices Sheena, is married to Paul Scheer, who voices Raymond the Cloud in episode 108B.
The voice of Sheena is provided by June Diane Raphael, an Upright Citizens Brigade veteran who plays Jane Fonda's daughter on the sitcom "Grace and Frankie."
"Weird Al" Yankovic, the voice of Mr. Sun, is a 2018 recipient of a star on the Hollywood Walk of Fame.