"LOVE that idea.Very cool.

I guess maybe it could be achieved through some morphing type special effect?

But then how would the remainder of the scene play out? Would that only be a momentary reveal or would the evil face be there throughout the battle and Anakin's turn?"

Thanks for the response. The reveal could go either way:

1.The momentary reveal would be a cool way to catch the Jedi off guard as he attacks them. The Force lightning part of the Mace-Sidious duel would still need to be removed. Once Mace has been killed, Sidious reverts back to his true evil/deformed face as he talks to Anakin.

2. His evil face could remain from then on since his true identity has already been discovered. The Force lightning part of the Mace-Sidious duel would be removed as well. (The problem would be to maintain his evil face throughout the duel).

Later Sidious could then manipulate the Senate (again) by lying that his deformed face was the result of a Jedi attack.