My personal favorite episode. It's got so much going on:

• Summer and Morty adventure.

• Patton Oswald and Christina Hendrix cameos.

• great high-concept-scifi in Unity's hivemind. It not only illustrates what it would be like on an controlled individual scale, but also the benefits and consequences of such a population. Loss of individualism and free will seem terrible, but then we are reminded how terrible society can be when left to their own devices.

• Star Trek references.

• References to Harmon's obsession with both redheads and giraffes.

• Rick and Unity's relationship is significant. It's progressive in terms of sexuality (i.e. Rick being involved with every age, sex, gender, various animals, etc). It explores the idea of being in an intimate relationship with an entire planet's population. It also examines how relationships change people and can amplify self destructive behavior.

• the ending is pretty emotional. It's probably the most depth we've seen to rick and it's genuinely sad. His suicide attempt is legitimate (despite failing).

• music tops it off.