Unlockables
Music Player

Beat the game once, then the music player will be available in Extra at the main menu.

Glitches
Easy Walse Castle Basement Looting Glitch

This works only on the Gameboy Advance version of Final Fantasy V. After so many steps, you are automatically thrust into battle. However, if you quicksave, exit and continue, the step counter is reset. If you take only 5 steps, a few more if you're feeling risky, save and load, you can get all the treasures and get out without encountering a single Jackanapes. Like this, you don't have to run if you are going for the Brave Blade and you do not have to encounter the Jackanapes on your first visit to the castle.

Secrets
Bonus Dungeon Location

Once you have collected all the legendary weapons and beaten the game load your cleared game save and head towards Phantom Village. Just south of there you will see bubbles on the water use your sub to dive under the bubbles and you will see the entry to the bonus dungeon.