Chris Hemsworth, Natalie Portman and Tom Hiddleston say the film also gave them a chance to be kids themselves.
"It's so fun to just get to be part of something that kids love, that like a really wide audience loves. There's something magic about being part of real, pure entertainment," Portman said.
Hiddleston says it's the size of kids' imaginations that draws them to the genre.
"I remember as a kid myself, I will never forget it, watching Christopher Reeve as superman," Hiddleston said. "I think that children have such huge imaginations and these films play into that."
Christopher Eccleston, who plays Malekith in the film, says acting in the movie reminded him a lot of his childhood.
"The reason 11-year-olds can tell you what the film is about is because in order to be in them, you've got to be an 11-year-old," Eccleson said. "When I'm doing green screen, for instance, and acting to a piece of tape or a tennis ball on a piece of string, I'm basically doing what I did as a kid when I played in the garden or pretended I was an explorer in the North Pole."
"It's about play, really. It's playful, it's imaginative and it's supposed to be fun," Eccleston added.
The film takes place one year after the events of "The Avengers." Thor is now battling a primeval race that is out for revenge and intends to plunge the universe into darkness.
"Thor: The Dark World" opened Thursday night and earned a very strong $7 million.
