Ah, but then there's the question of whether the characters know what the author does. It's one great weakness of world building that if your characters don't know it, it's a trick and a half to tell it to the readers. But one of the ways to add thickness to the world is know things they don't. . . perhaps someone could observe that something didn't work.

There's a good scene in the midst of Xanth where Dor is commenting on how their neat models of magic have broken from collision with reality.