Orianna R bug

After spectating the Reason Gaming vs n! game, I realized that the Orianna ult from Takefun at the baron seemed to be a bit too fast, so I played around with her a bit and found the following:

Normal behavior: Orianna casts Q and when the ball stops, you can cast W or R. The cast will only be possible when the ball is about to stop.

Bug: If you cast the Q over a wall (didn't try short walls, only reconstructed the situation from the video), you will be able to cast the R, before the ball is in place. The Ult will be avalable right when the balls leaves the wall, triggering the effect when the ball lands at its destination. That way, you can skip the wind up time of Orianna's ult, giving the enemy no time to react.