Final Fantasy - Did You Know Gaming? Feat. JonTron
The game was originally planned to be called Fighting Fantasy, however, at the time of the game's development there was already a series of roleplaying books and board games of the same name, so the title was ultimately changed to Final Fantasy.

This contrasts with the previously rumored false claims that Final Fantasy got its name after series creator Hironobu Sakaguchi felt that it was his last chance to make a successful game, and he was ready to quit the game industry and go back to university, making it his 'final' game.
Contributed by KnowledgeBase
Pressing A and B 55 times while on the ship will unlock a hidden sliding puzzle game.
Contributed by DeerBoarDude
The miniboss Eye or Evil Eye resembles the monster Beholder from "Dungeons and Dragons" and was named Beholder in the original Japanese version of the game. Due to copyright concerns, it was renamed and redesigned for all other versions.
Contributed by Cavery210
The spell Saber (SABR in the NES version) does nothing in the NES version. In later releases, it increases the caster's attack by 16 and the caster's accuracy by 10.
Contributed by Shinitenshi
The spell Temper (TMPR) was bugged in the original NES version. In later releases, it raises the attack of an ally by 14.
Contributed by Shinitenshi
In the NES and PS releases of the game, Intelligence had no effect on a spell's strength. A Red Mage can do as much damage with a fire spell as a Black Mage, and can use a cure spell as well as a White Mage, even though a White Mage should be better at it.
Contributed by Shinitenshi
In the NES release of Final Fantasy, there is a glitch in Cornelia Castle where the player can trigger a text dialogue without there being a sprite to talk to.
Contributed by Shinitenshi
In the English version of the game, just outside the city of Elfheim/Elfland are three tombstones, one which reads:
"Here lies Erdrick

Erdrick is referenced a lot during the game Dragon Quest, and is also the hero in Dragon Quest 3.

In the original Japanese version of the game, the tombstone is actually a reference to Link from the Legend of Zelda series. In later remakes of the game, the reference has been changed back to Link.
Contributed by DidYouKnowGaming