Hmm, I had no problem with the mouse.
Be nice if it showed the end score after game over.
Tested if you could force the ball out of bounds. It responds well in most cases and brings itself back.
But you can do it, for instance moving fast in the bottom corners and forcing the ball through.
I did that on first try quit easily.
What I did also do while testing that was accidentally throw the bat outside, which did not come back.
Easily repeatable when moving fast a and letting go, which you do naturally.