Thor: Ragnarok introduces the MCU to the planet Sakaar, and that’s the first indication of the comic series Planet Hulk’s influence on the upcoming film. In Planet Hulk, written by Greg Pak, Hulk finds himself being held prisoner on the planet and he’s forced to fight to survive. This is accomplished with an obedience disk that was placed inside Hulk while he was weak from his ship crashing on the planet. In the film, it’s Thor who is imprisoned there and needs to escape. We see from the trailer that Hulk is there, too, as they enter the arena for battle. So while the roles are changed slightly, the influence is immediately noticeable.
Hulk being banished from Earth in Planet Hulk is one of the sources of his anger. If he’s on Sakaar for Ragnarok, the scenario is likely similar. In the comic, members of the Fantastic Four and the Avengers made the decision to send Hulk away. Due to Fox having the rights to Fantastic Four, they’ll probably have to either skip that part of the explanation for Hulk being there or just alter it slightly to reflect what they’re able to use. Another thing of note is that he’s stayed the Hulk for a while after being banished. We already saw in Age of Ultron how dangerous he is when he can’t be convinced to turn back into Bruce Banner. Expect to see a similar effect on him in the film.
From what else we see in the trailer, we know that Thor needs help protecting Asgard. With Hulk just simply being present in this film, it’s reasonable that Thor would recruit him to not only escape Sakaar, but to help him save Asgard. Besides, would Hulk be on the movie poster if he didn’t have a fairly prominent role in the crisis that’s going on? Probably not.
Planet Hulk is one of the best Hulk comics out there, so it’s great to see them using pieces of it in the MCU. Even if it’s not strictly a Hulk film that we’re seeing, it appears as though they’ve plucked out some of the strong points from the comic to being to life on the big screen. In a conversation with CinemaBlend, Mark Ruffalo makes a mention of a Hulk story arc that starts with this movie and runs through the third and fourth Avengers movies. If that is in fact in play, we could see the Hulk have a more interesting story arc than he ever had in a solo film. Thor: Ragnarok doesn’t look like it’ll just be a good Thor story, but a Hulk one, too.