The thing about canon for a property that becomes long-lived and sprawling is that it has to be mutable. Obviously the major stuff should stay intact, but minor changes are inevetible. It's best when they make it work, but sometimes it will serve the story better to just move forward anyway, and sometimes they may just miss it too. I mean, there is just so much content! I know Dave and Pablo are like living Wookiepedias and all, but even they can't know everything.