Lone Wolf from FFV appears as a thief being held in Figaro's prison who later takes Mog hostage. Gogo also debuted as a puzzle boss in V.
Moogles. They first appeared in FFIII and reappeared in FFV, both of which were only given Western releases long after FFVI. They first appeared in the U.S. in Final Fantasy Adventure (only as a status effect) and later reappeared in Secret of Mana (as both a status effect and NPCs), as well.
The original SNES release was not released in Europe.
The Steam release for the PC is not available in Asia.
Referenced by...: Zero Punctuation uses Terra's sprite to represent old-school (but not old-timey) graphics in the "Fortnite/Dusk" double-bill episode. Yahtzee also points to FF6 as the last JRPG he could actually stand to play.
Throw It In!: Kefka's introductory cutscene after Terra's flashback (specifically the part involving his boots being sandy) was not in the original script; it was ad-libbed by Yoshinori Kitase in order to give players an early implication that Kefka doesn't have all his marbles, and also because the scene seemed boring without it.
Trolling Creator: In the Cave to the Sealed Gate, there's a treasure chest positioned in such a way that players who go straight for it will trigger floor switches that destroy two paths to it. When you get to it in a round-about manner, the chest turns out to just contain a switch that is actually a Kaizo Trap, removing part of the bridge up ahead until you go back and re-flip it. Thankfully, the developers weren't foolproof here — a player who outsmarts the floor switches and gets to the chest without hitting them essentially glitches the trap up and the bridge won't be removed when they come to it.
Before the Aerith revival rumors became infamous, there were the General Leo revival rumors. Myths abounds about ways to revive Leo in the World of Ruin and he would permanently join the party. The most common rumor was that if one killed so many Tyrannosaurs in the Dinosaur Forest, they'd encounter a dragon (a belief prompted by a mistranslation of what the thieves on the Veldt say, specifically referring to a dragon in the forest that was meant to refer to the dangerous monsters in general) that dropped a potion that could revive Leo. This is sometimes combined with the CzarDragon rumors (next point) by claiming he was the dragon players would encounter. Years later it was found you can get Leo in the party, but it requires a very complicated glitch and comes with many restrictions on how he can be used.
Hacking the game revealed the existence of CzarDragon, an apparent "boss" of the Eight Dragons. The main theory on how to encounter him was to Petrify the Blue Dragon (which is impossible) and you'll get the Raiden Magicite without giving up the Odin Magicite. When you beat the Eight Dragons and get Crusader, you now have all the Magicite pieces in the game and will be thrust into a rematch with the Eight Dragons, who are now stronger than before, finishing off with CzarDragon entering the ring. This was sometimes combined with the Leo revival rumors by claiming one had to defeat CzarDragon to resurrect Leo.
Game Genie users found that it was entirely possible to have a party with Kefka and Gestahl in it, though they were largely non-functional and shared a character portrait with Terra. This is caused by various scenes in the game where they appear in-battle as their Super-Deformed sprites (as opposed to the static enemy artwork), which necessitated coding them as some equivalent to a party character. Suffice to say, this led to rumors that it is possible to recruit them into your party. The above are parodied by an infamous list of "unlockable characters" which starts with General Leo, and ends with Ryu from Street Fighter, with increasingly-bizarre and impossible requirements for each.
The GBA release of the game featured censorship of the scene with Celes in prison. In the original release (worldwide), Celes was beaten by her guards while still in chains. The GBA version removed the beating and showed her unchained. After fans confirmed that this cut was in the Japanese version as well, speculation that the scene was censored due to mirroring a real life kidnapping in Japan ran rampant for years. Eventually, the game's translator, Tom Slattery, revealed the explanation is far more mundane: Square were angling for a CERO-A content rating in Japan for the re-release, but violence against a restrained person nets you a much-higher age rating under CERO. CERO didn't exist when the game was originally released, and thus the content wasn't considered as racy in the early 90s.
Early on, there was speculation as to what might be unlocked after finding Cyan's "Book of Secrets" in the World of Ruin. Years later, it was finally put to rest when it turned out to be a censored Porn Stash.
The game was one of the first 24mb cartridges for the console, but several events still had to be cut due to space limitations. They are known through sources like old V-Jump articles:
Most famous is the exchange between Strago and Shadow in a bar. Strago demands to see Shadow's face for Relm's sake, to which the Shadow unmasks with his back to the camera. The scene is also illustrated in a Carddass.
If time runs out in the laser-ravaged Tzen (World of Ruin), instead of a standard Game Over, Sabin was planned to die in the collapsing house and disappear for good. Bringing Edgar to the site would lead to him spending all night trying to dig out his brother, even though too many in-game days have passed after the fact. This was considered too dark and was removed.
During development, Terra was originally conceived as a 20 year-old male (but still a half-esper) who is Locke's partner-in-crime. Parts of this concept were later incorporated into Zidane and Tidus. In concept art, this character heavily-resembles Squall.
Terra was also intended to die during the game's ending.
Long-considered a 16-bit game par excellence, VI was originally going to be set entirely in Terra's world (dubbed the "World of Balance" by the fold-out map which came with the SNES cartridge). An April 2019 interview in Famitsu revealed that the game was initially intended to end with the heroes stopping Kefka before he could destroy the world. But the game was completed way ahead of schedule, so Square doubled its length with the free-roaming"World of Ruin", caused by the Empire disturbing the Warring Triad.
According to some storyline concepts, Celes was originally going to suffer from mental instability similar to Kefka due to the flawed Magitek process, but she would have overcome it. In addition, she actually was intended to be a Double Agent who infiltrated the Returners (albeit a conflicted one). They reused that concept for Cait Sith in the next game. Notably, other characters speak of her as a "traitor", but what she actually did to earn the ire of the Imperials is never brought up in the story, likely the result of a last-minute cut.
Gogo's recruitment was also different. Originally, you will run into a doppelganger of one of the party members in random towns. To recruit Gogo, you would have to bring his/her double to meet them. The Siegfried "imposter" makes a bit more sense in hindsight.
Relm was going to paint Yoshitaka Amano artwork, and later paint a mural depicting the party's adventures in the ending.
One of Square's initial plans for VII was to make it a direct sequel to VI.
The CzarDragon rumors (see Urban Legend of Zelda) were helped along by a lot of dummied content that made the rumors seem credible; there is dummied battle text for several members of the Eight Dragons' powering up in some way, text for each of them calling in the other for back-up, and of course the CzarDragon itself. When the Gameboy Advance version came out, the new bonus dungeon Dragons' Den contains rematches with the Eight Dragons, who use the same gimmicks described in the dummied battle text, and the boss of the dungeon is KaiserDragon, which shares its Japanese name with CzarDragon and uses a modified sprite of it. And then when you beat Kaiser you unlock the Soul Shrine, a gauntlet of 128 battles ending with the Eight Dragons and Kaiser. The dummied assets make it clear that Dragons' Den and Soul Shrine, or something like them, were planned for the Super NES release, but left out for time or technical reasons.
Word of Saint Paul: Soraya Saga was one of the scenario writers of the game and the person responsible for creating Edgar and Sabin. She wrote a doujinshi which detailed the background history of the Figaro family such as the death of King Figaro and Edgar's mother issues. She also wrote that the reason Sabin, Gau and Cyan got along so well was because they found a surrogate family with each other. However, Square has not confirmed or denied how much of that is considered canonical, and Saga even said it's just a side story.