It is a different story then, so the original HpMor would still not be nonfiction in another universe. For all we know, the existance of a corridor tiled with pentagons is in fact an important plot point and removing it would utterly destroy the structure of upcoming chapters.
Nnnot really. The Time-Turner, certainly, but that doesn't make the story uninstantiable. Making a logical impossibility a basic plot premise... sounds like quite an interesting challenge, but that would be a different story.
Here's the new thread for posting quotes, with the usual rules: