Hemsworth fought hard to bulk up to Thor-size proportions. Some said that multiple suits of armor were created for the actor because his body kept changing.
"I think they made more costumes because we kept destroying them in the battle sequences, ripping apart," said Hemsworth. "I mean holding that kind of weight for me isn't unnatural. My body does want to shed it. I've got to eat a lot. And if the schedule would get so intense that I couldn't do that, then some of the weight would drop away, and we would have to make adjustments with the suit."
Natalie Portman is also back as Thor's love interest, Jane.
"I think it's what the Marvel movies succeed at so much is just making it really like an enjoyable movie experience, and such a big part of that is humor," said Portman. "It's so fun to just get to be part of something that kids love, that a really wide audience loves. There's something (magical) about being part of real, pure entertainment."
Tom Hiddleston returns as Thor's less-than-trustworthy brother, Loki. He thinks the film works for the young and young at heart.
"I think children have such huge imaginations, and these films play into that. They want to believe in space, spaceships, gods, monsters, heroes and villains, and I hope there's still a kid in everybody who can tap into that and enjoy the film," said Hiddleston.
"Thor: The Dark World" is rated PG-13.