I learned this lesson many years ago, from of all people, a politician. He said there is only one way to get yourself out of a hole. Admit you don't know, say you'll go and find out, and commit to when you'll get back to them. Following that advice has stood me in good stead for years, and is one of the three key pieces of advice I give to junior staff as 'words to live by' (not just work by). The other two are 'never work longer than 105% of the hours you're paid for' and 'you can learn something from everyone, even if it's how not to do things'.

The best bit about graciously handling these situations is that it builds trust. Not every is actually out to screw you. Yeah they are pissed cos they saw an issue and they felt they weren't being consulted, but that can be turned around into a big win. Candidly saying, 'Tim, you have a great point, and we absolutely need to look into that' will pay off big time, especially the next time you deal with Tim (he now knows you take him seriously).

Being able to admit you are not omniscient, or have even made an out and out mistake is an incredibly powerful thing. Just so long as it doesn't happen too often!