1 Mercutio: So let me get this straight. In our original timeline Peter Jackson filmed the original rambling mess that was The Lord of the Rings.
2 Mercutio: And you, Will, were contracted to write a novelisation based on those films.
3 Mercutio: But then we went back in time and you rewrote Tolkien's original drafts to tighten up the narrative, thus creating the classic we know today.
4 Mercutio: Yet now, in this new timeline, nobody has filmed that version.
4 Shakespeare: Yeah, weird, huh?

This strip is what's known as "explaining how the story is fully consistent with past facts, after a reader points out that it got seemingly self-contradictory there for a while."

This does imply that these characters now inhabit a timeline different to our own. But then that was kind of always the case, as William Shakespeare is probably not alive in our current history.

These sorts of things are bound to happen when you write a serial story that messes with time and history. Actually, you could probably just drop the last 6 words of that previous sentence.