[Execution] A PO is wrong and the supplier is already acting on it. What do you do?

I would move fast, but I would not treat it like a generic fire drill. I want to know what is wrong, what the supplier has already done, what cost or timing risk now exists, and whether the mistake is still reversible. Then I would align the supplier and the internal team on the corrected version as quickly as possible.

After the immediate issue is...