This is the first entry in the core seriesnote If we go outside of the core series, the first instance would be BS Zelda no Densetsu for the SatellaviewSuper Famicom, in which Princess Zelda was playable in which the player gets to control directly a character other than Link, even if only for a very brief section: Namely Kafei, in one moment during his side quest.
Creator Breakdown: The very concept of the game and the sequence when Link is turned into Deku Link are coincidentially based on daydreams and nightmares. The stress of the deadline Eiji Aonuma had to make a Zelda game in a single year gave Aonuma nightmares, one of which involved Deku. The next day, the scene director showed him a scene he created for the game, which was just like Aonuma's nightmare; they decided to keep it in. As for the concept of the game, it was partially inspired by Yoshiaki Koizumi's daydreams, where he would wonder what it would be like if the moon suddenly fell down to Earth, and how people would react.
A few placeholder graphics for the other instruments, presumably meant to replace the ocarina graphic when you are transformed, were found hiding in the ROM, along with some location intro cutscenes that are never used. These were restored in the 3DS version of the game.
Executive Meddling: The game was originally supposed to be an expansion to Ocarina of Time, titled "Ura Zelda", and would use the Nintendo 64DD hardware add-on. However, when the designers expressed displeasure with this idea and the Nintendo 64DD failed, they were challenged to make an entirely new adventure in 1 year.
Oni-Link for Fierce Deity Link. He is almost only known by that name in some countries. note This is because of a Lucky"Blind Idiot" Translation of 鬼神 (Kishin), as the first Kanji on its own (鬼) means Oni.
The original was released in the US just before Halloween, which is appropriate given the game's mask motif and dark themes.
The 3DS remake came out on a Friday the 13th, which also suits the game's macabre tone, and the fact that many characters in the game suffer bad luck and curses.
New Work, Recycled Graphics: To cut down on development time and resources, the game recycles many assets from Ocarina of Time, most notably reusing character models for the majority of the extras. One area where the developers goofed with this is the arch at the entrance to Romani Ranch, which is the same as the one at the entrance to Kakariko Village in Ocarina of Time, including sign with Hylian text that translates to "Welcome to Kakariko Village''. The 3DS remake fixes this, however.
Serendipity Writes the Plot: The developers only had a year to complete the game (which is very short compared to the other Zelda games), forcing them to reuse models and sound bites from Ocarina of Time to save production time. They justified this by having Majora's Mask be set in an alternate Bizarro Universe of Ocarina of Time.
The game began development for the N64 add-on called the 64DD (or the "Nintendo 64 Disk Drive"), and was going to make use of some of the add-on's features. The game would have used a real time clock instead of the in game one, and was going to use a full 7 day week instead of three days like the final game (the 7-day cycle was later shown during the 2020 Content Leak), but these were dropped from the final product since there were difficulties trying to get these features to work on standard N64 hardware (even with the required RAM expansion pak). There was also a proposed feature regarding being able to literally buy time from a merchant, but the change to the clock system and lessening of days made the merchant seem less important.
Instead of the Fierce Deity's Mask, there was going to be a mask in the game that would have let Link turn into his adult self from Ocarina of Time (evidence of its existence can be seen in really early screenshots). This mask was scrapped for being mostly useless since all major equipment could be used by young Link this time around. Not wanting to let the "adult Link" aspect go to waste, however, the developers put in the Fierce Deity's Mask instead as a 100% Completion bonus that's required to use on the final boss in order to see the Golden Ending. Remnants of this idea include the fact that Fierce Deity Link reuses adult Link's voice clips and model (not textures), as well as an unused mask depicting Link's regular face.
Early screenshots display various changes to textures throughout the game. A small example is that the Deku Pipes originally were colored white instead of brown, but a much bigger example is some of the wall textures for both inside and outside of Clock Town. The textures originally were a bit more surreal with weird-looking suns, but in the final game the walls textures instead got somewhat less surreal looking designs. Perhaps another very interesting change is that Link was originally going to have the Kokiri Shield from Ocarina of Time return in place of the Heroes Shield (or perhaps as an alternate starting shield), and the Kokiri Sword originally looked exactly like how it did in Ocarina.
Originally, separate icons were used in the HUD for each of Link's instruments (which change depending on which form he's in). The final game just used the Ocarina icon. This idea would be revisited for the 3DS remake, which did have separate icons for each instrument.
Early screenshots showed the Megaton Hammer or something like it as Goron Link's weapon. This was replaced by a simple punch for the final game.
One image taken from the earliest stages of development showed that all three Gorman Brothers were originally one character, and originally worked for Cremia on Romani Ranch.
Before release, the game contained something called the Inspector's Mask, and you were to receive it from Mr. Toto. This mask did not make it into the finished game, and what it would have done remains unknown; however, considering Mr. Toto is familiar with Kafei's mother, and that Kafei's mask allows you to ask people where he's been, it could just have been an earlier version of that.
Shigeru Miyamoto told Famitsu that there was going to be an enhanced fishing mini-game. In the game, Link would be fishing for the legendary Jabu-Jabu—the Terminan version of the whale/fish deity from Ocarina of Time of the same name. If he managed to catch the giant fish truly bizarre things would happen, such as halting the fall of the Moon, or rupees raining from the sky. The fishing minigame would later be implemented in the remake, and it is possible to catch a rare fish that resembles a smaller Jabu-Jabu named "Lord Chapu-Chapu," though nothing spectacular happens when you do.
The 3DS remake has unused models for Ganondorf, Sheik, and Impa in its files, with their filenames suggesting that they were planned to be involved with the fishing ponds in some way.
Word of God: In a 2015 interview with Nintendo Dream, Eiji Aonuma claimed that the character designer, Takaya Imamura, named Majora (whose Japanese name was ムジュラ - Mujura) after the last two syllables of his surname plus an extra syllable from the name of Jumanji. In addition, Termina itself was essentially named after the type of buildings we call "terminals".