I know I can edit comments within a couple of minutes of posting them, but sometimes I realize an embarrassing mistake too late. I could always delete and repost, but that messes the order of the comments and all votes are lost. Is there a way to edit comments later?
You can't edit your comments yourself once the initial edit window of five minutes has closed.
But moderators can edit any comments at any time — in addition to being able to delete or undelete them, to move them to chat, and to turn answers into comments. If you think something should be edited in a comment (e.g. a blatant typo in a very visible and well voted comment), raise a flag and ask a moderator to edit. Choose the custom flag type and explain. Alternatively, you can also flag the question or answer the comment is related to — with a custom flag.
On a small site like ours this gives us negligible amounts of extra work. Of course some moderation is in order with such requests, but we trust you to judge well.
You can also flag other people's comments for the same reason! I have fixed obvious errors in comments before, and I'll be happy to continue doing so when pointed out.
I should also remind that comments are secondary content on this site and everything important should be written into questions and answers. Comments can be deleted with a relatively low threshold.