OK, I spent the past few days replaying KH, and I beat it today, and I noticed this oddity. After leaving Hollow Bastion, you have to go get a special Navi-G piece which Cid hid in order to return, right? Cid says he hid it 9 years ago when he first got to Traverse Town. Nothing wrong there, right?
Well, as you all know there are barriers to all worlds which were destroyed by Ansem, as recorded in his report. Ansem discovered a secret door and opened it, and he then noticed a "meteor shower" made up of gummi blocks - this was obviously a Gummi ship landing, able to do so as Ansem had broken the barrier to other worlds. The next entry in his report says he spoke to a King who arrived in a Gummi Ship about the Keyblade (Obviously King Mickey). And we all know what happened the day after Mickey disappeared: Donald and Goofy set out on their adventure, and thus do the events of KH begin.
So if the world barriers broke one day before the proper adventure of KH began (Or presumably when Ansem appeared to Sora in the Destiny Islands and then later when the Heartless attacked), how in the heck did Cid arrive at Traverse Town 9 years previously?