Rumors and leaks

There are a few rumors regarding content inside Splatoon. Some of these are created by the community, while others are sparked by the developers themselves.

Ongoing rumors
This is a list of rumors that have neither been confirmed true nor false.

NEW Splatoon Weapon DLC Leak
There was a leak announcing 33 unused and unannounced Splatoon Weapons and 2 unused stages

Splatoon Weapon DLC Leak
There was a leak on the internet for the Splatoon Weapons Guidebook that confirmed the DLC weapons known as Carbon Roller, Custom E-Liter 3K, E-Liter 3K Scope, Inkbrush, L-3 Nozzlenose, N-Zap '85, N-Zap '89, Rapid Blaster Deco and Splash-o-matic. Many of these weapons were, in fact, released through early updates, and thus it can be expected that the rest will be released in later updates.

Cheat Code
Some days after the game's launch, players noticed that some Sunken Scrolls, as well as signs on Inkopolis Plaza, contain what appears to be arrows pointing up, down, left or right.

On the 9th of June, 2015, the official Splatoon Facebook page made a joke post referencing how some Facebook users accidentally type Google search queries on their Facebook profiles. This joke, however, sparked curiosity amongst fans, as the "search" was for "Squid Jump cheats". Naturally, Nintendo staff themselves would not be searching for cheat codes on a game made by their company, meaning the post was placed there on purpose, likely to hint players about the existence of a code hidden inside the game.

On top of this, the official Splatoon Tumblr account made a post about how players can press [ZR] on the Plaza to look around, and how this serves the additional purpose of getting information on Miiverse posts. It also mentioned that it "may also have another use", which remains unknown to this day.

As of yet, no code has been found, and it is unknown if there is any relation between the arrows, the rumored code, and the rumored extra function of the [ZR] button, or if any secret exists to begin with. Players have since been attempting to figure something out by input the arrow's directions during different parts of the game, mostly the Squid Jump minigame, but without luck.

New Super Mario Sunshine Rumor
There is a New Super Mario Sunshine Rumor for DLC

Super Mario Sunshine Rumor
There was a "leak" on the internet that Super Mario Sunshine amiibo DLC was coming to Splatoon. Only a single image existed regarding this supposed leak. It has since been proven fake, with the author of the leak releasing the images they used to create it.