Typos and second chances
No matter how many people read through the galley proofs of a book before it goes to press, some errors manage to sneak through. We just found a few new typos (as opposed to the old typos, which we had already found and-or corrected) in an upcoming edition of American Sniper. And we just did a substantial overhaul on Silver Bullet, which is now available as a Kindle download.
Why and how do these things get through?
Authors are notoriously bad at proofreading their own work; the eyes see what they want to see, and anyone already familiar with the book - writers especially - will miss even the most egregious errors because of this. There are also glitches that get in due to problems in different versions of files used; I've had uncorrected files substituted for correct ones (don't ask), which can be really frustrating.
Perhaps the most pernicious, though, are the ones that occur when something is corrected, creating a different mistake. If you see a wrong verb tense or a number agreement problem, you've probably found evidence of that.
Of course, writers making changes on the proofs - tweaking as we call it - cause a great deal of those sorts of problems, whether we're doing it on hard copy ("can't read his @#$!! handwriting") or electronically. So it comes back to us in the end.
All of which is a long-winded way of saying thank you not only to the copy editors and proofreaders employed along the way, but to readers for helping rake up the ones that get through. (And please accept my apologies in advance.) But as a teacher once told me: The only thing we truly own in this world are our mistakes.