Fan Nickname: The game is widely known as "EarthBound Zero". Its North American release was canceled at the last minute, and the Dub Name Change title, Earth Bound, was later reused, albeit without the space, for the SNES sequelMOTHER 2. When a prototype of the game was discovered and dumped, after a few modifications to get it to work properly on the emulators of the day, the releasers tacked "Zero" onto the title screen to differentiate the release from the nonfunctional ROM releases, also acting as a nod to it sharing the name of its sequel, and the name stuck.
Fan Translation: At the time of the discovery of the English prototype, a group of fans had been working on their own fan translation; eventually, they were the ones who obtained the prototype and released the ROM to the general public, and for a while there were those who saw that as somewhat suspicious. Full story here.
There was also a Fan Translation of the MOTHER 1 portion of the Game Boy AdvanceCompilation Re-releaseMOTHER 1+2 that brings the text more in line with the original Japanese version, such as making all the towns named after holidays, as well as renaming Giegue to his proper international name, "Giygas" in order to tie it in with its sequel better.
No Export for You: The NES version is a particularly interesting case - it was complete and ready to go, then it simply didn't happen, likely because it arrived at the end of the NES's lifespan. The GBA version could be because of the legal issues said to doom the franchise's western presence, but it could simply have been out of lack of perceived interest.
Word of Dante: The live-action commercial's depiction of Ninten is the basis of a vast majority of fanart of this game - adopting his neckerchief and slightly different clothing here as a way to differentiate Ninten from Ness, who is by far the more famous wearer of their standard clothing.
Killer App: Not in its initial release, but many people - fans of the series or not - are considering buying a Wii U for the sake of its Virtual Console port.
Marth Debuted in Smash Bros.: Ness was playable in all three Smash Bros. games before EarthBound was released in Europe's Virtual Console. He doesn't have as much spoilers as Lucas does, though.
No Export for You: None of the MOTHER games have been released in Europe. And of the three MOTHER games, only this, the second, was released in the US, and even then only once.
The GBA compilation containing this game and its predecessor was only released in Japan, despite the fact that the original version of one game previously had a North American release while the other had a complete English translation that was only scrapped due to the age of the system it was on. As above, there was a brief consideration of releasing it in America, which didn't pan out.
Though at long last, it has been averted. Close to nineteen years after its release in North America, EarthBound finally saw a release in Europe via the Wii U Virtual Console.
It should be noted that while for MOTHER a straight script-dump from the NES prototype to MOTHER 1+2 would be possible, the same could not be said for EarthBound. After the release of the MOTHER 1+2 partial fan translation, in which the EarthBound half went pretty much untranslated, Tomato discussed why he wasn't going to do the EarthBound half properly: because both are so densely and strangely programmed, in completely different ways no less, that it's pretty much impossible.
However, TheZunar123 is currently making a Mother 2 translation for Mother 1+2 which can be patched along with Mato's fan translation, here is the link to it: http://youtu.be/sMWUOa46JGI
Screwed by the Network: One of the most egregious cases in gaming. Only one third of the entire series ever made it to American shores, and the infamous marketing campaign ("this game stinks" was the marketing slogan) likely put a dent on sales. Even in Japan this appeared to be the case, although it was finally released for the Wii U's Virtual Console in March 2013. However, it was also confirmed that EarthBound would finally be getting a Western re-release on the Wii U Virtual Console - in Europe too, no less! - with Nintendo of America engaging in a hearty dose of Lampshade Hanging.
Screwed by the Lawyers: Supposedly, the reason the game had issues being released in the US and Europe is due to copyrights concerning the name of an enemy (Dali's Clock) and two music tracks sounding like Chuck Berry's Johnny B. Goode (New Age Retro Hippie theme) and The Who's Won't Get Fooled Again (the Skyrunner theme). Apart from toning down the flashes during battles, the Virtual Console release has no changes from the original SNES release.
Too Soon: Surprisingly averted; the fact that the Aum Shinrikyo cult released chemical attacks in Japanese subways at the time of this game's release did not affect the inclusion of the Happy Happyist subplot.
Tuckerization: Due to the long nights he worked to get the game localized, Nintendo of America allowed Marcus Lindbloom, the game's localizer, to rename one of the minor NPCs to "Nico" after his daughter, who had just been born.
What Could Have Been: As there's a Dummied Out sprite in the game's code of Everdred's Ghost, it's possible that Everdred really was supposed to die in the game.
Ness's dog King may have been planned to join him several other times throughout the game besides the beginning part. It's given away by an unused climbing sprite.
Development Hell: The game started out as being a Super Famicom game shortly after the release of EarthBound, and was then moved to the N64DD, then the N64, then delayed several times until finally being canceled. It was ultimately revived for the GBA.
Urban Legend of Zelda: Using the silver dragonfly item against Negative Man is said to yield an extremely rare and valuable item. For those wondering Negative Man does actually have a 2% chance of dropping a meteorite which is worth 2500$, but this is unrelated to whether or not you use the silver dragonfly.
What Could Have Been: MOTHER 3started life as aNintendo 64 title, which was rather widely previewed and received significant press attention both in Japan and internationally, and Nintendo of America seemed pretty dead-set on giving it an international release. DCMC was originally supposed to have a female vocalist, and Kumatora's outfit was surprisingly more Stripperific; most of the cast's appearances and clothing were fairly different. Ness may have been set to appear in it, or perhaps Lucas was intended to look identical to him much as Ness was identical to Ninten. The N64 game was also supposed to be a lot Darker and Edgier—mostly due to the fact Itoi was suffering from depression at the time. This version of the game was widely called EarthBound 64 by both Nintendo and gaming press, so more often than not it's still called that in discussions to differentiate it from the released GBA version. Despite its extensive previewing at various Nintendo and game events, it never got very far. It was stuck in Development Hell for a very long time, and Shigesato Itoi was, not being very knowledgeable about computers, very ambitious with the project.
One of the most famous sequences from the 64 version which didn't make it into the GBA game was a sequence where Claus and Lucas rode a cart through a mine shaft. In the game, they're separated in Chapter 1 and never reunited until their duel at the finale.
Not even the Game Boy Advance version is free of this trope. Some sprites were found with Porky in a different machine and some of those sprites of him in that machine when put together make a glass shattering animation which looks like his defeat was different from the final version which could mean that you originally were able to kill him off before they changed it to where he escapes in and traps himself in the Absolutely Safe Capsule forever.
There's also unused sprites of Flint actually killing the Mecha-Drago instead of leaving it alive, which suggests that he was going to turn out Not So Different than the beast, as well as sprites of Kumatora as a Magypsy, suggesting that she was supposed to be the final Magypsy instead of Fassad.
Also judging from the information gathered by hackers, Flint is able to equip some of Lucas's strongest weapons, which may suggest that he was going to either be a permanent party member, or rejoin the party late in the game.