Marriner was gutless in the second half:
Scholes should have gotten a second yellow, Vidic should have picked one up for the cynical foul (he was expecting it from the grin on his face), and Valencia should have gotten a yellow for abuse after being warned for it by Marriner.
I'm amazed he gave two yellows anyhows, but the moment Everton went ahead the decisions were all going United's way.