So yeah, her scar is actually on the wrong side of her arm in New Moon, from where she was bitten in Twilight. LOL
Here, in Twilight, James bit her on the outside of her wrist (near her pinky finger).
But in New Moon, they put it on the inside of her wrist (near the side that's closer to her thumb).
well... at least they put it in the right general location of her body.... hahahaha...