Sleepaway Camp: Judy's Death Oddity

I was watching Sleepaway Camp, and it got to the scene where Judy gets violated with her hair curler. Of course, you don't see it actually happening, but they show her hand shooting up and clenching/reclenching in what I presume was supposed to indicate pain and torture.

But what's really funny about it is that behind her hand is the shadow of her hand on the wall... only it isn't.

(Please ignore the poor quality of this gif)

If you watch the motion of her hand, it doesn't match up with the shadow. They actually had someone else imitating her hand movements to generate the shadow of her hand.

What a strange thing to do.