Brooker said in an interview with the Black Mirror Cracked podcast that season four is peak Easter egg–hunting territory for superfans. "As people have appreciated that more, we've leaned into it," he told the hosts. So we scraped each episode, read interviews, and dove deep into the labyrinth of Reddit for every reference to other Black Mirror episodes and pop culture we could find.

The pure volume of Easter eggs has all but confirmed a long-running theory that all of Black Mirror takes place in the same twisted techno-dystopia. “We always used to say it’s a shared universe, but then I started to say it’s a psychologically shared universe and now some of the episodes are definitely connected because there’s specific references within that story to things we’ve seen in other episodes," Brooker told Express.co.uk. “So it sort of is now.” That's the extent that Brooker will talk about it so far, but the piles of evidence below speaks for themselves.

"USS Callister"

-- This whole episode was a big reference to Star Trek, so it’s like an Russian nesting doll of Easter eggs. The whole premise of “USS Callister” references the original series’ flaws, such as how its treatment of women and race hasn’t aged well.

-- Elena Tulaska (Milanka Brooks), the woman at Callister’s front desk, uses the dating app from “Hang the DJ.”

-- Kirsten Dunst—who's engaged to Jesse Plemons—has a brief cameo in the Callister office.

-- When gushing to Nanette Cole (Cristin Milioti) about Space Fleet, Daly tells her the show is now on Netflix. (Sure, it’s a navel gaze-y joke, but maybe the streaming giant has earned it.)

-- As spotted by Reddit user Gaijira, Daly boots up his computer with an OS called Ono-Sendai. It’s named after the computer Henry Chase uses in William Gibson’s iconic novel Neuromancer, which popularized the term “cyberspace.”

-- The office is on the 13th floor—which is the name of another cyberpunk classic, pointed out by Redditor HairyFotr1.

-- The planets Skillane IV and Rannoch visited by the USS Callister crew are named for Victoria Skillane and Iain Rannoch, the criminals from “White Bear.”

-- Raiman brand milk, Daly’s favorite beverage besides skinny lattes, calls back to a soldier named Raiman from “Men Against Fire,” who talks about her family farm. Apparently, it’s a dairy farm.

-- Director Toby Haynes revealed a few Easter eggs to The Hollywood Reporter: “Michaela [Coel, who plays Shania] had to be in a red outfit because she’s the first of the crew to get killed. On Star Trek, the guy in red always gets nailed. [Daly is also wearing red on the ship.]”

-- Haynes also said that Jesse Plemons had a vocal coach on site to help him perfect his dialect, inspired by William Shatner’s Captain Kirk from the original Star Trek series. “We did it one or two times where he went full Shatner, like when he says 'Fire' in the opening. That’s straight out of Star Trek VI: The Undiscovered Country. I love those movies. I’m quoting my heroes. So it comes from a place of love. We’re not punching down, we’re punching up.”

-- He also pointed out a few Star Wars references: “When Cristin wakes up in the medical bay, the way the lights came on was a reference to Gareth Edwards’ Rogue One trailer—the shot that never made the movie, when Felicity [Jones] is standing up and the lights come on in sequence... The tube that Jimmi [Simpson] goes into when he reactivates the engines of the spaceship, I wanted that to look like the tubes of the Bepsin in Cloud City in The Empire Strikes Back, the tubes that Luke Skywalker falls down inspired that... When Daly has just turned Michaela into an alien where he says, ‘Take that thing to the bridge.’ That’s the same line they say about Chewbacca when they are on the Death Star in A New Hope.” Check out the full interview here.

-- The “King of Space,” in the final sequence, a.k.a. Gamer691, is Breaking Bad star Aaron Paul. Notably, he reunites with Plemons, who played Jesse Pinkman's neo-Nazi captor. Paul also seems to be channeling his role as Todd Chavez in Bojack Horseman instead as he shouts, “Are we gonna blow each other, or are we gonna trade?”

"Arkangel"

-- Sara has a Waldo lunchbox, referencing the cartoon TV personality turned politician from season two’s “The Waldo Moment.”

-- When being fitted with the Arkangel system, young Sara watches a children’s show called Shimmer and Shine on a streaming platform that looks a lot like Netflix. The show, produced by Nickelodeon, isn’t currently available on Netflix—but in the wake of Disney’s buy-in to Hulu, perhaps the streaming giant is tipping its hand toward a future relationship.

-- To test the Arkangel system’s stress filter, Sara watches military footage that appears to be cribbed from the season three episode “Men Against Fire.”

-- A poster hanging in Sara’s room references the rapper Tusk, who dies in “Hated in the Nation.”

"Crocodile"

-- Mia may have designed Daly's house seen at the end of "USS Callister." Redditor AZ_Enforcer23 noted that the designs on her desk match up with the aerial footage of his apartment complex.

-- “Anyone Who Knows What Love Is” by Irma Thomas is played throughout the episode. It is also the song Abi (Jessica Brown-Findlay) sings in the American Idol–like show from “15 Million Merits.” One character sings it for karaoke in season two’s “White Christmas,” and another croons a verse in season three’s “Men Against Fire.”

-- There's a PSVR in Mia’s (Andrea Riseborough) studio, spotted by Reddit user harrisonisdead. Brooker has extensively tweeted about his love for the device.

-- The newspaper article about the cyclist killed in the opening has a secret message for Easter Egg hunting nerds: "'Of course the real question is why anyone would pause what they're watching just to read a sentence in a printed out newspaper article', says a voice in your head—before advising you to go and share this finding on Reddit." Which u/AFellowofLimitedJest did. That article was published by UKN, a news network that covers the prime minister’s pig-fucking incident in the first Black Mirror episode, “National Anthem.”

-- Wraith Babes, the porn series from the season one episode “15 Million Merits,” is available in the video on-demand selection at Mia’s hotel. She instead chooses a production by Erika Lust, a well-known feminist adult filmmaker who is vocal about changing the industry. Good choice!

-- A title under the "Classics" category in the hotel's video-on-demand section pictures a robot bee from "Hated in the Nation."

-- Fence’s Pizza—whose automated car accident leads to Shazia’s investigation—is the same company that delivers Robert Daly’s pizza in “USS Callister.”

-- When Shazia visits Mia’s hotel searching for information about the car crash, the concierge reveals a strict privacy policy was enacted after a data breach lead journalists to the name a prominent man who was caught there with a male prostitute. That man was a judge on Hot Shots, the _American Idol_-like show from “15 Million Merits.”

-- The episode ends with a children's play rendition of "Bad Guys" from the musical Bugsy Malone, the 1976 film of which starred "Arkangel" director Jodie Foster.

"Hang the DJ"

-- The sublime, atmospheric soundtrack to this episode was composed by Sigur Rós and Alex Sommers.

-- The episode's title is a reference to "Panic" by The Smiths, which plays over the credits.

-- Redditor CallMeJono found that if you go to 44:40 of "Hang the DJ," the fourth episode in the fourth season of Black Mirror, Coach tells Amy to count to four. She does, ending at 44:44. This is tied to the fact that it's impossible to slip a stone more than four times—which Amy does as she abandons Coach in her swimming pool. That's a lot of fours.

-- The dating app from "Hang the DJ" also appears in "USS Callister" and the season three episode, "Playtest."

"Metalhead"

-- The dogs’ design resembles robots designed by DARPA-funded engineers at Boston Dynamics, known for their viral videos being mean to their lifelike creations. Maybe that’s why these computerized canines are out for blood?

-- The car that Clarke (Jake Davies ) hacks just before he dies has the logo for TCKR, the company that developed the digital afterlife of "San Junipero."

-- Redditor TonyMoca found this gem hidden in the startup sequence of the car that has a list of other Black Mirror episodes, as well as a special message for Easter Egg hunters:

LOADED: \BMS1E1.drivers.tna.pigpoke LOADED: \BMS1E2.drivers.15mm.bing.abi LOADED: \BMS1E3.drivers.tehoy.men LOADED: \BMS2E1.drivers.brb.attic LOADED: \BMS2E2.drivers.white.bear LOADED: \BMS2E3.drivers.waldo.mt LOADED: \BMS2E3.drivers.white.xmas LOADED: \WHY.did.you.bother LOADED: \PAUSING.this.you.freak

-- Bella (Maxine Peak) finds a San Junipero postcard in the luxurious house in which she hides from the dog.

-- The white bears revealed at the end of the episode could be a reference to the [season three] episode, “White Bear,”—although Brooker told Entertainment Weekly that they’re actually yellow. Nevertheless, he adds, "I was happy with that being a little Easter egg. "

"Black Museum"

-- This episode was one big bone to throw at superfans who love sifting through every frame to find those sweet references. There were also a few so obvious, even casual watchers couldn’t help but get in on the game. References to episodes from every season are glimpsed as exhibits throughout the Black Museum. Here are the ones we found:

The artist who hung himself in “National Anthem”

Mugshots of Victoria Skillane from “White Bear” and production designer Joel Collins, which he points out in an Indiewire interview. Jane Fonda's iconic 1970 mugshot is also on display , as pointed out by u/SophieBulsara

The hood and hunting costume that Baxter (Michael Smiley), Victoria's torturer, wears in "White Bear"

Daly’s DNA uploader from “USS Callister,” along with Tommy’s lollipop

A sign that reads in bold letters, "Cloning Without Consent" references Daly's crime in "USS Callister"

The game from "Playtest"

Roach corpses from "Men Against Fire"

One of the robotic bees from “Hated in the Nation”

The bathtub in which Mia murders Anan Akhand, Shazia's husband, in "Crocodile"

Marie’s smashed Arkangel tablet

-- The hospital where Rolo scouts for victims is called St. Juniper’s, a reference to season three’s “San Junipero.” He also works for the company that developed the virtual world, TCKR.

-- Rolo explains consciousness transfer and the concept of cookies introduced in "White Christmas," and Nish asks if it’s, "Like when they upload old people to the cloud," referencing the technology in "San Junipero."

-- The Dr. Peter Dawson subplot is based on a short story by Penn Jillette called “Pain Addict.”

-- The lab rats from "Pain Addict" are named Hector and Kenny after the two main characters from season three’s “Shut Up and Dance.”

-- Dawson experiences death secondhand while trying to diagnose United States Senator Whitley (Mark Kempson), who is poisoned by Russians. Haynes remarks that Whitley was involved with "that whole thing," which The Wrap theorizes is a reference to Robert Mueller's investigation into collusion between the Trump presidential campaign and Russia. Brooker has spoken about how Trump's election impacted the series, so it's not too farfetched.

-- A news ticker during the second story spotted by Redditor too_wit references "National Anthem" with the line, "PM Callow marries pig," and "Metalhead" with the line, "Autonomous military 'dog' robot unveiled."

-- “15 Million Merits” shows up as a graphic novel in Rolo’s second story.