CGO sings the theme song to TV's 'Frasier.' The theme to the series 'Frasier' spun off from, 'Cheers,' was sung by Simon/Ice King in a previous episode (possibly the use of this song was a nod to the fact that "Distant Lands" is a kind of spin-off from the original 'Adventure Time' series).
As in the original series, BMO spends most of the episode with a young adventurer with a backpack and pointy white ears (Finn/Y5) and a shapeshifter (Jake/Olive).
Mr. M shares many similarities with Martin Mertens, including a love of gadgets and the same voice actor (Stephen Root).