I recently submitted a paper to a respectable journal. After submission, I discovered a few errors in my paper, one of which is quite serious. I have the corrected expressions and plots and I've checked that they are in agreement with the overall theory (as presented in other papers). My supervisor also agrees with me that I made errors and that I have now fixed them. However, this was AFTER submission, and I have not heard from the journal any more than an automatic update telling me that the referees passed my paper and that it's awaiting approval from the editorial board. Apparently the refs didn't catch my mistake. I desperately want to correct my mistakes. I would feel very bad if the very first paper I've written goes to print with serious errors which I am already aware of. I asked my supervisor if I should contact the journal, but he thought that that would mess up the publication process and that I should wait for the journal proofs and then follow their guidelines for fixing the paper. As far as I understand the journal instructions though, they only want minor changes so that the paper *looks* right, and not any extra information that changes the original paper (that's what the refs should take care of...). They also seem to have a very narrow time window for replying with modifications to the proof. So now I'm sitting here, really wanting to correct my first paper, but the refs didn't catch it, the supervisor's advising me to lay low and I have no idea how this is going to play out. Thought, anyone?