Homer nods, but copy-editors should be ever vigilant
We readers will swallow virtually anything. Talking animals? Fine, and not just in children's books: what about Animal Farm and Watership Down? Ghosts, monsters, stories set far in the future or on other planets, novels set in the unknowable past such as Golding's The Inheritors? Fine, fine, fine. Of course they won't be to everyone's taste, but essentially there is almost nothing that we can't accept as long as the writer can pull it off.
It's not the big things we baulk at, but small inconsistencies or anachromisms. As long as the internal logic isn't breached we can stay immersed in the story. John Gardner in The Art of Fiction, his classic work on the craft of writing, calls it the fictional dream. We don't want to be jolted awake and reminded that what we are reading isn't real, that someone, and a falliable someone at that, made it all up. This happened to me on a memorable occasion years ago when I was reading an engrossing novel - oh, alright, it was The Pilot's Wife by Anita Shreve. I can't remember the precise details, but on one page a character was, let's say, 67, and a few hours later she was 72. This little surprise pulled me out of the book. More recently, I read a novel where a character had recently taken 'O' levels (no-one has done that since the 1980s when they were superceded by GCSEs) even though the novel was clearly set in the 2010s.
All writers make mistakes and I am no exception. Editors, copy-editors, and eagle-eyed friends have saved me from various clangers. And with both these novels I got over it and read on. But neither author was well-served by their copy-editors who really ought to have spotted these bloomers. I suspect that publishers in general have cut back on both editing and copy-editing, expecting that - far more than in the past - agents will sort out this kind of thing and that manuscripts will arrive without needing much more attention.