I played a set game of straight pool on Monday on a drop pocket SAM table. When my run ended my opponent proceeded to take out the last half-dozen balls. However, neither of us had moved any of the balls that were in the one, now full, corner pocket. When he powered a ball in to the said pocket, in order to break a cluster, the object ball clipped the very top of one of the pocketed balls and bounced back on to the table. No other balls were moved by the offending phenolic resin sphere, so I let him have it.
I'm not sure how this would be dealt with in tournament play, but this wouldn't have happened on a ball-return.