I just discovered that in fact I believe that up to the paperback, it's fixable, the paperback is the immutable copy, because that's the one normal readers buy.

I think a lot of people think it's fixable up to the mmpb--I always look for the little line on the copyright page, "This book contains the complete text of the hardcover. Not one word has been omitted," and it's more often than not absent. Though even still I would expect consistency tweaking and typo fixing, not major things.