darquegk said: "It's been a while since I read Maguire's novel, but doesn't the musical hint that the widely-accepted story of "The Wizard of Oz" is in-universe propaganda?"
No, not really. It's a retelling of the original giving the story more of an adult twist. But even if it were so, there is no alternate reason the Cowardly Lion, Tin Woodman and Scarecrow would join Dorothy on her journey to get Courage, a Heart and a Brain (which they obviously all already had, brilliant on Baum) and thusly off to the Winkie Country to kill the Wicked Witch. There is no way a serious film could reconcile Boq and Fiyero's characters unless they give them alternate reasons for doing this (maybe Fiyero's on a covert mission...?)