RPGs like Secret of Mana are big and complex enough that they seem to be just rife with little oddities and glitches that are waiting to be unearthed by the intrepid player.
Take, for example, the town at the beginning of the game, Potos. The boy character is tossed out of town fairly early on in his adventure and told never to return... at least not until he's done saving the world.
But, you can get around him. Or, rather, you can get through him. Just wait until you have multiple people in your party and come back to the village. Then press and hold Up while pressing Select. You'll cycle through control of all your characters and slowly inch your way through this gatekeeper.
Now why you'd want to do such a thing is beyond me, since the stuff in the shop is no better than you'd find anywhere in the world, and everyone still hates you anyway for dooming the village.
Oh, but make sure you have the Flammie Drum before you get in, or you don't mind resetting the game. That guy that's keeping you out? Turns out he's pretty bad at his job, but very good at keeping you in.