"But that e-mail - the one he'd overlooked - said his clients were supposed to be paid $425 million - $25 million more than he'd written in the contract."
I think the last part of the sentence "$25 million more than he'd written in the contract" has a grammar error. I think it should be "$25 million more than what/the money/the amount/ the number (etc.) he'd written in the contract."
Am I right?