'Twilight: Breaking Dawn's' Kristen Stewart Tells Jay Leno How She Smacked 'Snow White' Co-Star Chris Hemsworth (Video)

Kristen Stewart on Tonight Show With Jay Leno - H 2011

Chris Hemsworth apparently got a little more than he bargained for when he signed on to star opposite Kristen Stewart in Universal's Snow White and the Huntsman.

The actress, who is currently promoting The Twilight Saga: Breaking Dawn Part 1, appeared on NBC's The Tonight Show With Jay Leno on Thursday night, where she relayed a story about smacking the Thor star while shooting a scene in Snow White.

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"When they call action, it doesn't matter how times they say look, watch this, be careful with this, don't hit him in the face -- Chris Hemsworth -- which I did," Stewart told Leno.

"Thor? You hit Thor in the face?" Leno asked.

"It made such a loud sound. ... I was supposed to miss him by this much," Stewart said. "I basically knocked him right out of his close-up."

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Stewart added that the smack will "definitely be in the movie."

In the movie, Stewart plays Snow White to Hemsworth's Huntsman.

The project also stars Charlize Theron as the dagger-wielding Evil Queen, and Sam Claflin as a prince.

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Directed by Rupert Sanders, the film is slated for a June 2012 release.

Relativity also has a Snow White film in the works starring Lily Collins.

Meanwhile, Breaking Dawn, the penultimate film in Summit's five-movie Twilight franchise, opens Nov. 18. Robert Pattinson and Taylor Lautner also star in the movie, which was directed by Bill Condon and is based on the book by Stephenie Meyer.