The Twilight star, who plays the title character in the film, was required to shoot a series of her own stunts on horseback and she admits she was far from comfortable in the saddle.
Speaking to fans during a panel at the weekend's (17Mar12) WonderCon event in Anaheim, California, she said, "I got to jump off cliffs and ride horses, and that terrifies me. I was really, really not happy about having to do all that (horseback riding). I don't like that - I hate that.
"I hate 'em. I fell off a horse once and hurt myself really badly. I broke and dislocated my elbow when I was, like, nine."
But Stewart reveals she did her best to bury the memory.
She added, "I just had to not think about it. I wanted so badly to do this that it was just like, 'Alright, well, if I perish by horse, that's all good.'"