I'm currently reading the third Richard Stark 'Parker' novel, The Outfit. I've got two editions of the book (don't ask); this one:
The 1973 Berkley paperback, and this one:
The 1988 Allison & Busby hardback. The paperback I've been keeping in my bag, to read at work or when I get a spare moment on the move. The hardback sits in my bedroom, to be read... well, in bed. But reading two different editions causes one to notice the editorial mistakes that have crept in somewhere down the line.
Boring as it is, I've occasionally wondered where and how spelling and punctuation mistakes find their way into different editions of books from different publishers. Is it at the editing stage? The typesetting stage? Proofing? In the case of The Outfit, the A&B edition has a fair few errors that aren't there in the Berkley edition: a missed indent; a comma instead of a full stop; a 'the' instead of a 'that'. What I don't know is how those mistakes happened, or when. There were perhaps four editions of the novel in between the Berkley and A&B ones, so it's possible that it wasn't A&B who were being sloppy but previous publishers (although A&B still should've spotted them).
I guess things like this are what make every edition of a book unique. I also guess things like this are of absolutely no interest to anyone other than me. So it goes.