Some plot discrepancies (spoilers)

[Shiro]

When Luneth finds the Wind Crystal, his adoptive father Topapa tells him that he was brought to Ur as a newborn baby ten years ago. Luneth's age is given as 14...
The surface world was supposed to have been in stasis for 1000 years, yet Cid recalls his voyage ten years before that resulted in him being stranded on the Floating Continent with the four children. Quite a mix-up, eh?

[Zargabaath]

Regarding the 1,000 stasis I do have a theory about that. When the lower world is brought out of that stasis the people don't really recall waiting for a 1,000 years to unfreeze. Therefore to the lower world & Cid's airship it would seem like time had kept flowing.

For example: Time could have stopped for 1,000 years while I was typing this but I would not realize because with time stopped no particles would move therefore my brain would not register time passing. Resuming time I would think that time was flowing continuously, uninterrupted.

As to how they got out of the lower world. The theory for that was the two crystals [Wind & Fire] knew that those 4 children (Luneth, Refia, Arc, & Ingus) were the destined Warriors of Light and for 1,000 years they worked out releasing Cid's airship from the black fog/mist which was pretty close to the floating continent.

As for the other thing... I don't know. Maybe old man Topapa considers a 4 years old a baby being he is old.