Chris Hemsworth and Taika Waititi Reveal Their Kids Helped Create Thor 4 's 'Cool' Monsters

Chris Hemsworth and Taika Waititi's new Marvel movie is their most family-friendly yet because they involved many of their own family members in its making.

According to the Thor: Love and Thunder writer/director/costar, the fourth stand-alone Thor movie not only features cameos by several cast members' kids, but a "cool and weird" set of shadow monsters inspired by their hand-drawn designs. [Ed. note: This is not a spoiler, we promise!]

"Here's a fun fact, I haven't talked about this at all," teases Waititi, 46. "This is a world exclusive for you, PEOPLE magazine. The monsters in the film were originally based on drawings that all of our kids did. I was typing the script and my daughter kind of leaned over and she was like, 'What's an oil monster?' That's like the first thing I could come up with [when] I was writing. I said, 'I have no idea. I just wrote oil monster, whatever that means.' And she goes, 'What do you think that looks like? Do you think it's spiky?' And then she draws this like snakey thing."

Adds Hemsworth, 38: "And then Taika said to me, 'Tell your kids to do some drawings,' and they did some drawings."

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(Hemsworth is dad to daughter India, 10, and twin sons Tristan and Sasha, 8, with his wife, actress Elsa Pataky, 46. Waititi has daughters Te Kāinga o te Hinekāhu, 10, and Matewa Kiritapu, 6, with ex Chelsea Wistanley).

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Waititi explains that he then gave the drawings directly to the visual development artists working on the VFX for the film.

"They turned them into these fully rendered, wild monsters," he says. "In some of the kids [drawings], they were super colorful. So we toned those down. But yeah, that's why the monsters are so weird and look so cool. That's why the monsters look like they were created by kids."

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Hemsworth and Waititi also shared that all of their children were on set at some point during filming in Australia.

"Anyone who had kids in the cast had their kids on the set," says Hemsworth.

"I always encourage people to have their kids around because it's just a cool environment and it chills the crew out," adds Waititi. "And I always want work like that. But yeah, sometimes [Hemsworth] will be doing takes and you'd stop and go, 'Uh-oh,' because we'd hear something [off set in the background] and he'd be like, 'Is that one of mine? Or one yours?'"

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"You can get caught up in the sort of making a movie," says Hemsworth. "It's serious and there is pressure and whatever, and the kids come in and they just pull the rug out and they go, 'This is ridiculous, come on.' And it's a nice reminder and sort of shakes [you] into the present of this should be fun."

The father of three adds that his kids are generally not too impressed with dad's job.

"A friend of ours is a big wildlife-rescue conservation guru, and my daughter's obsessed with animals," he explains. "The other week she goes, 'I don't know why you don't have a cool job like Mark does.' I was like, 'What? I play a superhero!' She goes, 'That's pretend! He's saving animals in real life.' That's grounding and immediately humbling."

Thor: Love and Thunder opens in theaters July 8.