Why did the Emperor remain motionless while Darth Vader threw him off the balcony?

I'm wondering whether this was a movie sin but his body position seemed to stay the same? Also why didn't he stop using electric? He continued to use it even as he was falling down.

I'm also wondering whether Palpatine meant to electrocute Vader or was it just a coincidence (because he kept firing electric)

It makes no sense he just stood there allowing Vader to throw him.