I'm rather confused by everyone's rationalization. We do know one rule (paraphrased) from the official rules:
"If you choose an illegal maneuver on your dial (red manuever while stressed), give your dial to your opponent and he may choose any legal maneuver he wants."
From this ruling, I would think this rationale could be applied to rolling too many dice. If you made the mistake of rolling too many green dice, your opponent should be allowed to remove any of your green dice results he wants until the proper number of dice remain.
