The goggles that let people see through their alternative timeline doppelganger's eyes is the same one Rick uses to find a replacement universe after everyone gets Cronenberged in "Rick Potion #9".
One of the TV shows they watch calls back to the previous episode "Meeseeks And Destroy" and the planet Gazorpazorp.
Morty reveals his own grave in the backyard to Summer, explaining how he and Rick destroyed their own world in "Rick Potion #9" and crossed over to this reality mere moments after the local Rick and Morty died from one of Rick's inventions.
In "Something Ricked This Way Comes", Rick can be seen watching Ball Fondlers, one of the shows he and Morty watched in "Rixty Minutes," near the end of the episode.
Cronenberg Rick and Cronenberg Morty are members of the Citadel of Ricks.
In "Ricksy Business" there are two of the Councilman Ricks at the party.
In "Ricksy Business" there's a Mr. Meeseeks in the background of Blips and Chitz helping someone play an arcade game. When the game starts lighting up from some sort of jackpot, the Meeseeks winks out, his job complete.
After the events of "Ricksy Business", in which the Smiths' house gets transported to another dimension, from that point forward there is always a crack shown in the ground around the house from when it resettled after being transported back.
Season 2
Also in "Mortynight Run", a Hungry for Apples ad can be seen hanging over a vending machine.
In "The Ricks Must Be Crazy", Rick, Summer, and Morty visit a universe with a Ball Fondlers movie, which was first shown in "Rixty Minutes". There are also movie posters for French Toast (a piece of toast was part of Saturday Night Live's cast) and Three Brothers (a sequel to the nonsensical Two Brothers).
Also in "The Ricks Must Be Crazy", Rick opens a hatch on the leg of his mecha, releasing a snake, similar to the "snake holster" in "Get Schwifty!"
"Big Trouble in Little Sanchez" has Morty eating Strawberry Smiggles for breakfast. Jerry is also seen playing his iPad game again, there's a picture of Snuffles on the wall of the Smiths' dining room, and Morty has a picture of Jessica in his locker.
Season 3
The Season 3 premiere episode "The Rickshank Redemption" shows Summer digging up Rick's grave from "Rick Potion #9" (which she learned about in "Rixty Minutes"), along with a trip to the Cronenberg-ed dimension created in that same episode. Hammer Morty is also seen later in the episode, used by a Rick to kill Galactic Federation guards before being shot.
The stinger in "Morty's Mind Blowers" has Jerry finding a box for Jerry's Mind Blowers, which contains tapes labelled "Apples Campaign" and "Sleepy Gary".
Season 4
In the Season 4 premiere episode "Edge of Tomorty: Rick Die Rickpeat", when Rick dies, he is resurrected by Operation Phoenix in another reality, and expresses confusion at first, since he'd (literally) axed that program after the events of "Big Trouble in Little Sanchez" back in Season 2.
Beth and Jerry are still attending family therapy sessions with Doctor Wongnote who apparently still continues to see them and didn't dump them as clients even after Rick destroyed her office in the previous episode, who continues to give them solid advice.
"Mortyplicity": The weapon one Rick gives to a Morty is a laser-whip, which Morty previously begged for in "Promotyus".
"Rickternal Friendshine of the Rickless Mort": The whole episode is full of them, elaborating specifically on Rick and Bird Person's history, but it also has nods to other episodes:
Rick mentions Pickle Rick in the Cold Opening, admitting that a new plot is possible after the rest of the Smiths leave him.
In the season premiere, Morty asks Rick why everything has to be a fight with him. Here, he picks fights with his own self-built AI and his younger self.
The Battle of Blood Ridge is shown.
Through the exploration of Bird Person's memories, Squanchy, Tammy and Revolio Clockberg Jr return. The latter whose feelings Rick doesn't consider a true friend is likewise a nod to in-universe, with Rick mentioning the only reason any of them hung out with Gearhead, is because he was the little brother of their real friend Gear Dude. They felt obligated to hang out with him after Gear Dude died.
The formation of the band Rick, Squanchy and Bird Person were in is shown.
When they arrive at Bird Person's memory of Rick's garage, Rick finds Bird Person only remembered him having a Plumbus.
Rick warns Bird Person not to clone his kid and send one off to fight in space because they take that badly.
Rick's wheel of "Better Things Than Morty" has Kyle 2.0 as one of its options, likely referring to the same Kyle Mr. Nimbus mentioned in "Mort Dinner Rick Andre".
After Morty amputates his own hand to defeat Nick, Rick offers him a variety of different hands he could give him to replace it, and one of the options is to "make it big, like that one time."
When Beth wonders aloud where the original Rick and Morty from their dimension are, Summer rather casually responds, "Buried in the backyard," which Morty revealed to her in "Rixty Minutes" and she directly saw for herself and took advantage of in "The Rickshank Redemption".
This episode confirms that two Jerrys were swapped at the Jerryboree back in "Mortynight Run", which was heavily implied at the time, and they all realize it here.
Hermit Jerry references how he, Hermit Beth, and Hermit Summer were frozen by the SWAT Team Ricks in "The Rickshank Redemption", and mentions that Summer and Beth actually died as a result of this because the Ricks never bothered to unfreeze them (a monster thawed them by licking them, but only Jerry survived).
After the Earth has been overtaken by Mr. Frundles, the family moves to another dimension where their counterparts all died at the same time and end up being buried by their replacements, like in "Rick Potion #9".
Rick uses a cybernetic implant in his spine to inject drugs directly into his bloodstream, an ability introduced in "Claw and Hoarder: Special Ricktim's Morty".
The frozen corpse of Fat Morty from "The Ricklantis Mixup" can briefly be seen floating in space alongside other dead Ricks and Mortys.
In "The Wedding Squanchers", Rick makes the excuse that he's going to the Gloppydrop system for ice cream when he turns himself into the Galactic Federation. Here, both Beths make the excuse to go to the Gloppydrop system for some ice cream just to give themselves time away from the family. Apparently, Gloppydropulites make the single best ice cream in the entire galaxy.
The Beths decide to have their minds blown so they forget their affair, just as how Rick has been doing it to Morty. They don't end up going through with it, though, since Jerry emerges from his shell before they can.
When Space Beth leaves she says she will keep an eye out for her grandson in space.
Rick enters the episode in turkey form, apparently having gotten another presidential pardon for something.
Jerry and Beth both find that they're turned on by him being cuckolded, just like Jerry's parents. Also like Jerry's parents, they make the rest of the family very uncomfortable with it during a holiday.
Jerry's fetish for emasculation is foreshadowed as early as Season 2, where the couples therapy showed that their mental interpretations of each other (Jerry seeing Beth as a monstrous Xenomorph-like monster and Beth seeing Jerry as a spineless, submissive worm), despite being the worst couples' scenario the clinic had ever seen, actually worked perfectly together—as this episode shows, there's a reason their conflicting personalities work together so well.
Jerry also shows a high level of understanding of how Beth works in that episode (namely correctly guessing that Beth's ideal vision of Jerry as a muscular fighter would in turn view her as a literal goddess). He uses this to his advantage in this episode.
As the "Inside the Episode" video shows, Night Summer is echoing Rick when she says "Sorry Rick, but your opinion means very little to me." Rick previously said this to Summer in "Rick Potion #9".note Technically speaking, this would have been a different Summer—the original one from before Rick and Morty switched dimensions—but since they traveled to one that had near-identical experiences to theirs, presumably, the Rick originally living there said this to "our" Summer, too.
Night Summer is motivated to seize the day or "carpe all them diems", as Summer put it in "Rickmancing the Stone". Like Summer then, Night Summer gets the wakeup call that seizing the day means more than just indulging herself.
The blast shields from "Total Rickall" make a return while the Night Family has the Day family hostage.
In a Freeze-Frame Bonus at the very beginning, right before Rick sees the news story about the rift in space, an ad for Eyeholes cereal shows up on the TV screen.
Unlike the previousepisodes where it was brought up, this time, Morty will actually get to go to Boob World with Rick! (Offscreen, of course.)
In "Rickmurai Jack" we learned the Central Finite Curve sectioned off the multiverse to keep the adventures of Rick (and other Ricks) contained to the universes where he was the smartest man in the universe. With the Curve destroyed, this episode carries the implication that the universe the family moved to at the start of the season is one of the universes where Rick isn't the smartest man in the universe, demonstrated by the dinosaurs being even smarter than Rick.
During Jerry's funeral you can see Tricia Lange crying. For context, she wanted to have sex with him when watching him beekeep (he gets killed here by getting stung to death by bees) in the stinger for "Promortyus".
You can also see Jacob, Jerry's parents' lover from "Anatomy Park".
The twist at the end of "Never Ricking Morty" is that the Rick and Morty the audience followed for most of the episode—including the climactic face-off against Story Lord—were fictional versions of themselves that were generated as characters on a toy train that the real Morty bought for the real Rick. So when Story Lord and Jesus Christ return here, they're familiar with the titular duo, including the fact that the versions they fought last time weren't the real ones; however, Rick, of course, doesn't know who they are, and when Morty does recognize Story Lord after a minute, it's as "the villain from that toy train I bought you".
Rick still has his ripped, 6-pack abs that he got from working out in "Night Family".
Speaking of which, after Story Lord and Rick both rip their shirts off to show their jacked abs, Story Lord refers to them as "cum gutters", the same term that Story Train Morty used for them in "Never Ricking Morty". Just as Story Train Rick found it to be gross, the real Rick comments here, "I don't like that phrase."
Rick pulls out the butter robot from "Something Ricked This Way Comes", tasking it with pulling a lever. It is no less dismayed by this equally pointless existence as it was its first one.
Inverted by Connie TinuityError, whose power is the ability to literally break the episode's continuity (such as placing a stack of petroleum barrels at an exit previously established as unobstructed) in order to trap Rick and Morty.
Jerry references how Rick once turned himself into a pickle to avoid therapy in "Pickle Rick". In the same episode, Mr. Goldenfold was also shown to be one of Wong's patients, and we see him here in a therapy session with her. And he feels better after Rick briefly turns him into a fly — a creature known for consuming feces — referencing his struggles with eating poop from that same episode.
In The Stinger, when the Galactic Orbship debates adding Mr. Nimbus to their number, it's mentioned as a point in his favor that he can control the police, which was shown in "Mort Dinner Rick Andre".
Summer, Morty, and Jerry are shown eating Strawberry Smiggles for breakfast, which was first seen in "Rixty Minutes".
Jerry complains about Piss Master peeing on the lavender plants in the front garden because "my bees" need the lavender, referring to how he took up beekeeping in "Promortyus" (and has apparently continued doing so offscreen ever since).
A subtle one, but Rick previously commented "Well, I can't cure death" when Reuben died in "Anatomy Park", and it's been shown in multiple other episodes that he indeed cannot bring people back from the dead. Here, he tries to revive Piss Master after finding him dead in his home, but while he's technically able to resuscitate Piss Master, he can't reverse the damage to his brain.
Morty suggests moving to another universe when the solar war starts getting out of control. Unfortunately, Rick decides now would be a good time to resolve a problem instead of running away from it.
Rick utilizes another "Vat of Acid" gambit over the sun's flames to escape. This time, Morty doesn't complain, even accepting that this is their only option, and it works.
Rick references the previous episode, "A Rick in King Mortur's Mort", after the Robotic Reveal, confirming that he replaced himself with Rickbot after the events of the Cold Open after Morty called him boring, and Rickbot has been standing in for the real Rick ever since. Similarly, Rickbot takes a jab at his real counterpart: "It's almost like someone designed me to be 22% more thoughtful than you," a reference to his promise to Morty to be 22% more agreeable.
Like in "The Rickchurian Mortydate", a previous season finale that also involved Rick confronting President Curtis, Rick once again warns the President's staff not to touch something or they'll die, meaning it quite literally rather than as a threat. And once again, one of them doesn't listen to him, and does indeed die as a result, while Rick is quick to give them an "I Told You So".
Rick's end-of-episode tirade to Morty, where he rants about the future adventures they'll have together while Morty just listens and looks freaked out, resembles his previous similar rants in "Pilot" and "The Rickshank Redemption". The main difference is that those episodes were season premieres, talking about the adventures Rick and Morty would have for the rest of the season, while this one is a Season Finale and the rant is referring to next season's adventures.
The Fantasy chemical vats from "The Old Man And The Seat" return, which are the vats that Rick used to incapacitate Tony for using his private toilet. The room where these vats are contained is revealed to be on the third floor of Rick's underground laboratory. Morty's lightsaber breaks through one of the vats in its descent, freeing a tough four-armed lizard alien in the process.
As Jerricky prepares to leave for good, Summer asks if this is like the time "with the crows", referencing "Forgetting Sarrick Mortshall".
Memory Rick, Rick's 35-year-old memory self who's been living inside his mind since "Rickternal Friendshine of the Rickless Mort", apparently saved Rick's and Jerry's consciousnesses inside Jerricky's mind to keep them from being permanently fused, but ends up inside Jerry's brain instead of Rick's once the two of them are properly separated back into their bodies.
Once again, Morty's Black-and-White Morality in a very gray universe leads to severe consequences he needs Rick to fix after previously insisting on doing the "right" thing. He even promises to stop doubting his grandfather on these issues at the end of the episode.
Once the Cold Open is revealed to be Evil Morty's origin story, we then see a Fully Automatic Clip Show of "Close Rick-Counters of the Rick Kind", "The Ricklantis Mixup", and "Rickmurai Jack" from his perspective while building up to the present day.
A humorous example in a very dark episode: When Evil Morty goes to the Morty registry, the clerk tells him he needs to lose the eye-patch, as all Ricks have a fearof pirates.
Rick Prime's file for the Omega Weapon is titled "Booger AIDS", the same title Rick uses for all his files, as revealed in "Solaricks".
video shows, Night Summer is echoing Rick when she says "Sorry Rick, but your opinion means very little to me." Rick previously said this to Summer in "Rick Potion #9".note 