Voiced by Jeffrey Wright, The Watcher overseeing the events of What If...? comes from a powerful, cosmic group in the Marvel Comics — and we’ve actually met them before. The Watchers made their MCU debut in a Guardians of the Galaxy Vol. 2 post-credits scene as an unenthused audience to Stan Lee’s stories (ostensibly about the late Marvel scribe’s super-powered adventures). Not only did the brief scene tie The Watchers to Marvel lore in a major way, but it also foreshadowed the mysterious beings’ role in big events — perhaps not coincidentally, Vol. 2 premiered shortly before Thanos and his game-changing gauntlet wreaked havoc in Infinity War.

As Wright says in the trailer, though, The Watchers don’t get involved — they just, well, watch: “I observe all that transpires here. But I do not, cannot, will not interfere.”

If that line rings a bell, it might be because you heard something pretty similar in the Eternals teaser. Here, the immortal group says they “have never interfered — until now.” Apparently, only something as monumental as the Multiverse opening up could stir The Watcher and Eternals alike.

Incidentally, in the comics, The Watchers and Celestials (the cosmic beings from which the Eternals derived) oppose each other’s approach to influencing world events.

Doctor Strange’s Tilda Swinton will be returning for What If...?, and the Ancient One appears to narrate a significant moment in the series trailer. “Time. Reality. It’s changeable,” the sorcerer says, a possible reference to her conversation with Bruce Banner in Avengers: Endgame.

Bucky’s been through a lot — or at least, one version of him has. In the debut episode of What If…?, a much happier Bucky can be seen making jokes and enjoying life free from Hydra torture or train tragedies. However, the episode still makes several references to Bucky’s fate in Captain America: The First Avenger and The Winter Soldier. As Captain Carter tells him, “Maybe you’re just afraid of trains,” to which he nods in confirmation. (Of course, Bucky being canonically afraid of trains makes his original fall way more tragic, if that’s even possible). Bucky even tells Carter, “You almost ripped my arm off!” as they hop atop it. Ouch.

When it comes to favorite MCU lines, it doesn’t get much more iconic than Steve Rogers’ “I can do this all day.” As Twitter user fvalconss pointed out, Bucky says a variation of this phrase in Episode 1 of What If...?, telling his Hydra Stomper bestie that “we don’t have all day” before their final fight.

As Twitter user hiddlesbubbles observed, Captain Carter’s arrival in the modern-day by way of the Tesseract looked similar to Loki’s first scene in 2012’s Avengers. In both instances, Fury even tells the travelers to put down their weapons.

The tentacled Champion of Hydra may seem new to the MCU — but maybe not. We saw a similar monster called the Abilisk in Guardians of the Galaxy Vol. 2. In an iconic opening sequence set to “Mr. Blue Sky,” Drax and co. defeated the creature, which Gamora described as an “interdimensional beast.” And, of course, being powered by the Tesseract, the Champion seems to be pretty interdimensional itself.

Among the Collector’s many treasures and trinkets are an abundance of weapons from across the MCU. How they were obtained, though, is fodder for another What If…? story. Captain America’s shield, Mjolnir, and a Dark Elves’ dagger are just some of the intriguing finds in Episode 2.

The Collector also wields Hela’s iconic helmet and Necrosword, which Marvel describes as a powerful weapon created from a “proto symbiote,” aka the same kind of creature that appears in 2007’s Spider-Man 3 and the Venom films. Gorr the God Butcher, who is will be played by Christian Bale in Thor: Love and Thunder, also uses the weapon in the comics.

Episode 2 of What If...? might have focused on the Guardians of the Galaxy as helmed by T’Challa Star-Lord, but there were plenty of references to our favorite Asgardian of the Galaxy, Thor, throughout. The Collector punches T’Challa with an arm he stole from “a terribly chatty Kronan,” a nod to Thor’s friend Korg, and Nebula’s “adopted” line sounds a lot like Thor and Loki’s use of the word in Avengers and Thor: Ragnarok.

Meanwhile, several of the Collector’s artifacts potentially point to a very different reality for Asgard as we know it. There are Frost Giants, Elvish literature, a Dark Elves’ dagger, and Hela’s weapons all housed within the Collection. Could the Collector have taken them before they could do major damage to the characters and their home? Depending on where and when he came across those items, perhaps Asgard was spared some of its worst enemies in this particular universe.

The differences between T’Challa and Peter Quill’s Star-Lords don’t stop at their approaches to dealing with Thanos. As author James Foley pointed out on Twitter, T’Challa’s ship is now called Mandela instead of Quill’s Milano. They both named their ride after famous figures, but Peter went in a slightly different direction. As Guardians of the Galaxy writer and director James Gunn confirmed in 2014, Milano was named after Peter’s “awesome childhood crush,” Alyssa Milano.

The final shot of Episode 2 perfectly mirrors a scene from Guardians of the Galaxy Vol. 2 when Quill’s dad, Ego, plants a Celestial seed that’s key to his goal of taking over the entire universe. He did so behind the very Dairy Queen that Peter Quill is shown working at today.

Twitter user TheMrAlex wondered if one of the Collector’s artifacts was a nod to Star Wars, as it looks remarkably like one of the franchise’s famous X-Wings. It wouldn’t be the first time the MCU referenced Star Wars, of course — Peter Parker’s plan to take down Ant-Man in Captain America: Civil War was informed by the series: “Hey guys, you ever see that really old movie, Empire Strikes Back?”