The Legend of Zelda

The Legend of Zelda features Link on a quest to save Zelda from the evil Gannon (sic!). On his way, he gets no help at all, except for the Old Man who gives him a random stick he picked up somewhere (plus some vague hints), and is on his own in the vast land of Hyrule.

Unused Enemy Values
Monster modifier:
 * - Strong enemy that resembles Digdogger, only completely graphically corrupted
 * - Nothing? (Puff of smoke, may be replacement data for cleared-out rooms)
 * - Nothing? (Puff of smoke, may be replacement data for cleared-out rooms)
 * - Gleeok with one head.

Unused Spawn Type
Via the use of world scrambler codes, you can force enemies to spawn from an unused configuration; all the enemies will rush out from a single cloud of smoke.

Unused Push Blocks
Several rooms in the dungeons have push blocks that are impossible to move. It's possible that some of these rooms once used the blocks to open a door or secret passageway, and the blocks weren't removed when the room layouts were changed. Oddly enough, one block exists in the room where Princess Zelda is imprisoned, which doesn't make a whole lot of sense.

Heart Container Glitch
In the original FDS release (v1.0) there is a glitch that allows players to easily get a lot of extra Heart Containers. On the eastern shoreline there's a Heart Container that is normally only reachable with the Ladder, but if you use the Flute when standing in front of it you'll pick up the Heart Container when the whirlwind drags you across the screen, and the Heart Container will still be there when you return.

The number of dungeons you’ve completed seems to determine how many times you can do this, so if you’ve only completed two dungeons, you can only do this twice. The number of Heart Containers will still max out at 16, you can’t get any more than that. This trick is perhaps most effective on the much harder Second Quest where you obtain the Flute already in Level 2. Using this trick makes the game a lot easier not only because of increased life but the quicker you increase the number of Heart Containers the quicker you will be able to obtain the stronger swords. This was corrected in v1.1.

Title Screen
The PRG1 version adds a trademark symbol to the title screen.

Save Option Screen
The PRG1 release of the game adds a small warning to the continue / save / retry screen.

In the elusive Animal Crossing version of the game, this screen is a hybrid of the two original screens on the NES: the continue/save/retry options are condensed on the top area of the screen like in the PRG1 version, but there is no warning text due to it being unnecessary on the GameCube. It's worth noting that this is one of two games (the other being Super Mario Bros.) that are completely inaccessible without a game enhancer, such as the Action Replay.

English Localization
Some of the hints were changed rather than translated when it was time for the English localization of the game. The severe Engrish and odd reasoning behind some of the changes makes it unclear what Nintendo had in mind for some of the choices made.

Level 1
Literal translation: “You can’t use arrows if you run out of money.”

The hint in the Japanese version is a useful tip on how the Bow works, which you get in this dungeon. In the English version it was changed to a hint for a secret 100 Rupee location.

Level 5
Literal translation: “There are some creatures that are weak against sound.”

This hint is referring to the Pols Voice's weakness. Since the Famicom microphone controller was never released outside of Japan, the method to defeat Pols Voice was changed and this text change reflects this.

Level 7
Literal translation: “Spectacle Rock is an entrance to death.”

The hint for how to find Level 9 was for some reason moved to Level 8 (see below). "The tip of the nose" is apparently the room in Level 7 where a secret path to the boss' lair is found. A very odd choice...

Level 8
Literal translation: “Look for the arrows in Death Mountain.”

The English version's hint was moved from Level 7 and in the process replaced the hint for where to find the Silver Arrows. What?!

Literal translation: “Search for the Lion Key.”

The hint that you should look for the Magical Key in Level 8 aka Lion, was replaced with... not the most helpful of hints.

(The English line may be an attempt at a hint that if you defeat ten enemies without getting hit AND defeat the final one with a bomb, said enemy is forced to drop a set of four bombs. If you defeat the last enemy with the sword it will give you a blue Rupee instead.)

Level 9
Literal translation: “Have you found the Red Ring?”

The reminder that you should probably find the Red Ring was changed to a hint for how to find the Compass.

Literal translation: “Destroy the topmost boundary.”

The Japanese line may be hint for how to find the Red Ring but it's really vague and could as well refer to something else, maybe that's the reason it was ultimately replaced in the English version. (What's odd is that this hint was already in place in the prototype version of the game where all the items in Level 9 were still in different locations.)

Level 6, Second Quest
Literal translation: “There’s a secret north of a lake.”

Another really vague hint in the Japanese original that was replaced with something that made more sense - a hint for finding Level 8.