I think the First made it a Ref'ing nightmare.
With
Q603, where the boulder came from makes a difference.
Let's say that Red Robot shoots the high goal, and misses. The Boulder rolls and comes to rest in the Outer Works. That boulder is free to be picked up and shot again. Meanwhile, Blue inbounds a boulder, and it is somehow blocked and rolls around in the courtyard. The inbounded boulder is closer to Red Robot, so it goes for that boulder.
The Ref's will somehow have to keep track of which Boulders in the Outer Works have successfully crossed, and which ones have not.