Though Justin Roiland may not have been as well known both on and offline as he has since the incredible success of his animated collaboration with Community's Dan Harmon, Rick and Morty, it doesn't mean he's been slouching around.
It's well known to fans of the show by this point that Rick and Morty is the result of a mishmash of characters and voices created by Roiland over the many years of his body of work thus far. Many elements of the show are drawn from old or discarded works, from Rick and Morty themselves to the character of King Jellybean (from S01E05 Meeseeks and Destroy).
Even the theme song has its origins in an earlier piece produced by Roiland, an unaired animatic pilot called Dog World, created by Roiland for Cartoon Network back in 2012.
Dog World is the story of the affable Peter Michaels, his ill mannered brother Edmund and their innocent if unknowing younger sister Sally. During a camping trip the three are sucked through a wormhole and end up in a world populated by talking anamorphic dog people who keep animal-like humans as pets.
You might recognize the voice of Peter Michaels as Morty whilst the voice of Edmund (who from his name and personality I'm guessing is a nod to The Lion, The Witch and the Wardrobe) is closer to Roiland's take on the Earl of Lemongrab from Adventure Time.
The S01E02 episode Lawnmower Dog makes numerous references to the concept of this unaired show. The name of the Smith's dog in Lawnmower Dog is Snuffles (later Snowball) whilst the name of the Dog family, Mr and Mrs Doggerson's, pet human is Ruffles.
Towards the beginning of the episode Rick accidentally calls Snuffles Ruffles when putting the helmet on his head and teaching him to shake, a callback to Dog World.
But the most explicit reference comes at the end of the episode when Snowball and the rest of the dogs are leaving Earth via the wormhole to start their own planet, and this dialogue ensues between Rick and Morty:
Morty: "Wow! A whole world populated by intelligent dogs. I wonder what it'll be like, Rick."
Rick: "I think it will be great, Morty. You know... it could be developed in-into a very satisfying project for people of all ages. I mean, I'd watch it, Morty, for at least 11 minutes a pop. You know, may-maybe they'll do it board-driven."
Morty: "You know, that's a real comforting idea, Rick."
Rick: "Aaaah... What do you know, Morty? What do you know?"
Furthermore, in each show the father is called Jerry after one of Roiland's real life dogs, which actually explains a lot about Jerry's faithful, if dimwitted, personality.
And For Season 3?
Well it's no secret that Roiland likes referencing his previous work in Rick and Morty but up until recently we hadn't really seen any callbacks to previous show specific storylines, as each episode contains its own specific narrative.
This was deliberate, as Dan Harmon explains:
"Our instinct was; let’s not ruin this by curling back in on our own tail too soon. There are a couple of instances where the joyful TV viewer in me says we should’ve done another Meeseeks episode. But overall we had a very gun-shy approach of avoiding that temptation."
And so they did. The only real overarching story of the second season was the Bird Person / Tammy wedding subplot, but it looks like this episodic format might be about to change up a bit for Rick and Morty Season 3. Speaking of what the two creators wanted to include in Season 3 Harmon commented:
"I re-watched [Seasons 1 & 2] a couple nights ago, and now I'm excited about revisiting stuff in season three because I was so phobic about revisiting stuff in season two. Now, we can fade in on Blips and Chitz because we've already proven that the show isn't going to start eating itself, and that will feel even more limitless if we go back to a couple things that we really enjoyed doing."
Neither Harmon nor Roiland have confirmed which narrative elements they're going to call back to in Season 3 (though Harmon has promised a reappearance from one Mr. Meeseeks), but there's a lot of scope to revisit old characters and settings here now.
So will we see Rick and Morty traveling to Dog World as a callback to the unaired pilot that gave the show its now iconic theme song? Let's hope so, even if only so Morty can see Snuffles - I mean, Snowball - again.