Hi,
I had a mistake on my naturalization certificate. I did not even notice it when I got it. First of all, you will get the certificate only AFTER the swear-in ceremony and when you are walking out. If you notice the error, you can tell them on the spot and they will make arrangements for fixing it. Otherwise, I think you have 2 business days to get it fixed with a infopass. I realized the mistake (half spelled middlename) and I called to get an info pass. I got the infopass on the 3rd business day. But, I did not have any issues. This was in Boston. I went to the Boston office and gave my certificate to be fixed. They fixed the name and gave it back to me in 45 minutes. So, if you identify the error, you can get it fixed within 2 days.
Regards,
Shaji.