Funnily enough, I see nothing wrong with it.

Disguise's Theoretical Explanation: The gun was originally held in the left hand, but at a certain point in the animation cycle the two hands are at exactly the same place, meaning that the left hand is completely hidden from our point of view. It is at this point where the gun is swapped from the left hand to the right hand, the animation then proceeds with us only having the view of one hand (the right hand) while the left hand is concealed from our view behind the hair for the rest of the animation.

Evidence leading to this: The left hand is shaded darker than the right hand (see left leg vs. right leg for a comparison). If the left arm was actually on the other side of the hair we would see a darker shaded hand.

In either case, the arms never actually touch the hair, they move behind and in front of it. As for her bending in those strange ways, well...Lori is an athlete, and man oh man have you actually seen what gymnasts can do with their bodies?

They should rename gymnastics to 'Land of the Rubber People!'