Japanese version 1.0 to version 1.1
A significant bug exists in the Japanese 1.0 release which occurs during battle initialization. The programming beginning at SNES address 00896B checks memory addresses 7E1701-7E1702 to get the 16-bit value of the player's current location. If it's location 015A-015C or 0167-017E (all lunar dungeons), the game sets a flag to load a different table of enemy related data. However, the current location isn't accurate on a world map because of a shared memory byte.
On world maps, 7E1702 will continue to store the second byte of the last location visited, but the other half in 7E1701 is now used to store which world map you are on (00 = overworld, 01 = underworld, 02 = moon) The problem starts when you leave location 005A-005C or 0067-007E. These location values include the Misty Cave, Mt. Hobs west entrance, Antlion cave, Toroia basement rooms (use Exit spell), and the water dungeon caves between Kaipo and Damcyan. If you take the airship to the underworld, the result is you now have a current location in the 015A-015C or 0167-017E range even though you're not inside a lunar dungeon.
When you get into a battle on the underworld map, the game uses the wrong table and the enemy AI for most formations is completely broken. In many cases, the enemies cast Stone on themselves over and over until successful, and will never attack your party.
This bug was corrected in the Japanese 1.1 version by first checking if 7E1700 is 03, which signals the battle was started inside a dungeon and not a world map.
No other changes were made between Japanese version 1.0 and 1.1 besides the bug fix.