Mortyplicity

The song played in the post credits scene is "Who Wants To Live Forever" by Queen, which originally appeared on the Highlander - O Guerreiro Imortal (1986) soundtrack. Rick specifically named this film earlier in the episode when he said that the decoy families annihilate each other following "Highlander rules", because "there can be only one" (Highlander's tagline).

Rick refers to Ramirez in Highlander - O Guerreiro Imortal (1986) as being Spanish when the character was born in ancient Egypt. But in the 16th century era of Highlander he has a Spanish name, he had worked for the King of Spain and he was referred to as The Spaniard.

References Westworld: Onde Ninguém tem Alma (1973)