The following are known glitches in III.
NES version glitches
Numb status glitch
Often called the Dream Ruby glitch, because it can induce the numb status to a character, this glitch uses the fortune teller in Ashalam to alter memory addresses. Notably, it can be used to transform held items into other items, as well as alter the Zoom spell list to include locations not yet visited. This allows for large sequence breaks which can be used to complete the game very quickly. This glitch only applies to the NES version.
Companion overload glitch
This glitch involves recruiting the maximum number of companions using Ruida's Tavern. Once the capacity has been reached, The Hero will mysteriously know many spells which are not learned until later levels, including:
It is hypothesized that some memory addresses overlap causing this glitch. This glitch only applies to the NES version.
Several downsides to the glitch, however include the inability for the Hero to learn Heal and Return outside of battle & certain items disappearing from the inventory. The first Wizard spells for battle will also disappear from the list
Stat rollover glitch
When leveled up high enough, certain stats will roll over the limit of 255, resulting in extremely low stats for a highly-leveled character. This glitch applies to the NES version.
Silver harp glitch
If you play the Silver Harp in a Monster Arena, you will remove the top monster from the list of monsters in the battle. When you bet, you need to select the monster above the monster you want to bet on. So if you want to bet on the second monster, bet on the empty space, or if you want to bet on the third monster, bet on the second monster, etc. It will use the odds from the slot you selected.
Additionally, if you have under 65536 gold, then gain enough gold to exceed 131072 gold, you can exceed the 99999 gold limit. It will still display as 99999 though.
You will end up stuck in a glitched room, and have a party consisting of only your one dead character. You will be unable to move, use items, cast spells, or otherwise proceed in the game.
GBC version glitches
Pachisi level up glitch
This is widely viewed as a glitch, but does not seem to be as there is specific text in the game referencing its occurrence. This glitch occurs while playing Pachisi and landing on a space which causes the characters stats to go down, and the stat you lose is Strength. After this occurs, the next battle fought will result in a massive number of experience to be added to the characters total experience, causing him/her to automatically level up to level 99. However, it has been noted that these level ups are not the same as standard level ups, causing the level 99 character to only have the stats of approximately a level 75 character who is leveled up normally. This glitch only applies to the GBC version.
The chimaera bug (キメラバグ) affects the Japanese GBC version only. The bug can corrupt the memory that holds information about the party's second, third, and fourth characters. The bug can also be exploited to write arbitrary values into that memory.
The chimaera bug occurs after using a chimaera wing in the bag, then, rather than choosing a destination, pressing B twice to return to the bag. This temporarily maps any changes to the bag's memory into the first character's inventory memory instead. The first character's inventory has only 2 pages, so changes to the bag's third page and above overflow into the memory following the first character's inventory. Overflow memory includes the second character's name, class, stats, spell list, and so on.
The chimaera bug is fixed in the English GBC version.