In case you're not familiar with it, if you turn on the Walkthrough walls cheat code in both the DS and SNES versions, you end up in a strange glitched version of the Millenium fair. I think someone on the compendium itself suggested this may be a leftover secret passage for the unfinished Zeal dungeon that still exists in the coding in the SNES version.
When I tried it, I ended up on one of the Ocean Palace elevators with Magus now in my party, then eventually froze at the Mammon machine.
Anyone explored this?
On a similar note, what happens if you try to do the "Chrono" part of the Dimensional Vortex without Chrono brought back yet?