Guardians of the Galaxy looks like it's going to be a ton of fun, and apparently Marvel thinks that fans are really going to love it, because it just announced at Comic-Con that a sequel will arrive on July 28th, 2017. The announcement was Marvel's biggest surprise of the night, in what was otherwise a fairly quiet event in terms of details on its upcoming films.

Two new 'Ant-Man' actors announced

Its panel opened with a big sizzle reel of Marvel films that concluded with a quick tease of the villain Thanos. The cast of Ant-Man then appeared on stage to talk about their upcoming film, and they showed a short clip of test footage that was just long enough to wow the audience. Two new cast members were announced for Ant-Man as well: Lost's Evangeline Lilly will be playing Hank Pym's daughter, Hope Van Dyne, and House of Cards' Corey Stoll will be playing the villain Yellowjacket.

The crux of Marvel's event, however, was the cast of Avengers: Age of Ultron coming out on stage to talk about the film. Their discussion may not have revealed much, but a teaser aired during the event did. It began with members of the Avengers attempting to pick up Thor's hammer — naturally, to no avail — only to have Ultron bust up the party, turning things very, very dark, very quickly. What follows were some incredible fireworks, some Quicksilver and Scarlet Witch action, and even Iron Man in his Hulkbuster Armor.

To add to the festivities, Josh Brolin made an appearance onstage wearing a novelty Infinity Gauntlet, which ever so gently hints that the artifact will play a role when Thanos finally makes his official debut in Guardians next week.

ICYMI: THANOS teased with quick shot on his hover-throne-chair... thingy. #HYPE! pic.twitter.com/gYMyZoKUvd — Superhero Report (@SuperheroReport) July 24, 2014

Unfortunately, that was about all of the detail on its upcoming slate of movies that Marvel wanted to give. Marvel still has five movie release dates picked out for yet-to-be-named heroes: there was some hope that Marvel would announce a few of those tonight — potentially even showing that its films would begin to follow the trend of diversifying their characters, as its comic book lines are doing. But while we found out about Guardians 2, there's still a whole lot of mystery remaining on the subject of what's coming next from Marvel.

Kwame Opam contributed to this report.