Is it possible to make minor (making a space between two words) proof corrections after already submitting a proof reading to a journal? After submitting back an online proof reading corrections of an accepted paper, I found a very trivial mistake; just making space between two words. The words take vague meaning if left not spaced. Is that possible to make one more proof read to correct this typo error?
Email the production editor as soon as possible that you've found this extra correction. If it's still not inconvenient for them, they'll probably fix it. However, because it's such a minor error, you should be ready for them to say "it's too late" as well. This probably won't lead to an errata or corrigendum - it's just too minor.

If your previous reading had contained lots and lots of corrections, it's possible they're already planning to send you a set of second proofs.