Ragnarok may have happened, but the next huge, intergalactic battle is right around the corner. Thor: Ragnarok introduced fans to some important new characters like Tessa Thompson's Valkyrie and it injected some welcome humor into the normally self-serious Thor subsection of the Marvel Cinematic Universe, but what diehard Marvel fans are going to be looking at most carefully is one of the final scenes. Before the climactic final battle in the movie, there's a small Loki scene in Ragnarok that will be instrumental in Infinity War, the upcoming Avengers movie. Let's talk about that small moment in Odin's Vault that sets up Avengers: Infinity War.
Spoiler alert: Obviously, don't read this until you've seen Thor: Ragnarok or don't care about spoilers. While Loki is on his way to grab Surtur's crown to bring about Ragnarok and destroy Hela at the very end of the movie, we see him stop and glance at the Tesseract. As everyone who has been following the Marvel movies for a while knows, the Tesseract has a dangerous history with Loki. In The Avengers, the first Marvel team-up flick that came out in 2012, Loki used the Tesseract to travel between realms and rip open portals to other planets. It was the Tesseract's power that led to the climactic Battle of New York, which exposed the Avengers to the public.
After the Battle of New York, Thor takes the Tesseract back to Asgard along with the captive Loki, and it's been locked up inside Odin's Vault ever since. At least... until the last few moments of Thor: Ragnarok it seems. We don't actually see Loki grab the Tesseract while he is within the vault, but it definitely seems to be implied by the way that the mischief god eyed the powerful object that he pocketed it before all of Asgard got destroyed by Ragnarok.
Okay, so Loki (probably) has the Tesseract — how does this lead into Avengers: Infinity War? Well, the Tesseract is actually one of the six Infinity Stones, which will obviously be at the center of Infinity War. Hardcore fans already know that the Tesseract is actually the Space Stone, one of the all-powerful cosmic artifacts that the alien warlord Thanos will be collecting in the upcoming Avengers movie. We've seen Thanos mentioned (and even make brief appearances) in the past several Marvel movies, setting him up as the main villain of Infinity War.
The fact that Loki has the Space Stone also explains that post-credits scene, in which we see a gigantic spaceship block the passage of Thor, Loki, and the rest of the Asgardians as they left their exploded planet. Though it's unclear, it's pretty safe to assume that spaceship belongs to Thanos, who has shown up to take the Space Stone from Loki. After all, Loki did promise the stone to Thanos at the beginning for The Avengers, and has yet to deliver it. This could be the first of the Infinity Stones that Thanos obtains in Infinity War, which will come out next May.
The Space Stone isn't the only Infinity Stone we've seen pop up in the Marvel Cinematic Universe. The Power Stone (referred to as the Orb) played a major part in Guardians of the Galaxy), the Reality Stone (called the Aether) was a big part of the first Thor movie, the Time Stone (kept within the Eye of Agamotto) was used by Doctor Strange in his standalone, and the Mind Stone was another weapon used by Loki in The Avengers and eventually became Vision in Avengers: Age of Ultron. The only Infinity Stone we haven't see on the big screen is the Soul Stone.
Avengers: Infinity War will come out on May 4, 2018.