* FridgeHorror: Thanks to the {{Retcon}} in this game, those Balrons you killed in UltimaIV weren't demons in your way - they were innocent worshippers who were on a pilgrimage!
* GameBreaker: One unintended consequence of a certain combination of spells has given rise to the most awesome "legit" way of cloning rare equipment. Animate causes an inanimate item to come to life and acquire basic critter stats (low HP, defense, no attack, and mobility). If "killed," said animated object would revert to its nonliving state. The Clone spell would create a duplicate of any living object. Simply put, you can Animate Magic Armor (which would try to run away), Clone it a few times, then kill them all with a method of your choice.
* GoodBadBug: There was a bug allowing players to carry infinite inventory items regardless of weight. By opening a container item in a person's inventory, then using the 'Get' command to grab the item of choice. This would return players to the main inventory menu but now with the (normally weight-limit breaking) item in the inventory. This could be used to break the game from sheer quantity - objects, [=NPCs=] and world items would start to go missing.
** [[http://it-he.org/ultima6.htm This page]] has an exhaustive list of other fun stuff the programmers never intended.
* PolishedPort: The SNES port of this game was surprisingly good for a PC game converted into a console cartridge, and especially for a mouse-based interface converted to a controller interface. While there was censorship (the blood and alcohol was removed), and a few enemies and spells were removed due to size restraints, the game remained very faithful to the PC version. There were even a few improvements such as giving the menu its own screen instead of having take up most of the main screen, getting rid of useless items (such as mugs), making the KarmaMeter visible, bundling multiple copies of an item together instead of listing them individually, and making the balloon fast and controllable with the D-Pad.
** The FM Towns port added voice acting in both English and Japanese, as well as digital sound effects to replace the PC speaker sound effects of the original version.
* RewatchBonus: Due to the WideOpenSandbox nature of the game, upon starting up you can march directly to many beneficial places in the game, like the Pirates Treasure.