Easter eggs
Easter eggs are secrets in video games as a means of unexpected entertainment or a bonus.
The following is a list of easter eggs in Splatoon.
Great Zapfish at Piranha Pit
While playing on Piranha Pit, the Great Zapfish appears briefly out of the water on the far, lower west part of the map. If a player waits until there is one minute left, they will likely see the Great Zapfish. An E-liter 3K Scope scope is recommended for this,to get a closer view in zooming.
Basketball
On the Testing Area that can be accessed by pressing 
on the Equipment screen or whilst in Ammo Knights, there is a basketball hoop. If the player tosses a Sub Weapon, such as a Splat Bomb, into the hoop, their Inkling will say a celebration phrase, much like they would if they were to splat an opponent in Turf War. A green sparkling effect will also occur around the hoop.
Blooper and Octorok
Hidden in various areas such as Zone 4 are stickers featuring the sprites of a cephalopod-like enemy from another Nintendo series. For example, a Blooper from the Super Mario Bros. series and the Octorok from Zelda II: The Adventure of Link, the former being squid-like and the latter being similar to an octopus.
Password entry
Each number on the password entry screen for Private Battles plays a specific tone when the cursor is moved to it:
| Numbers | 5 | 0 | 6 | 1 | 7 | 2 | 3 | 4 | 8 | 9 |
|---|---|---|---|---|---|---|---|---|---|---|
| Note | Lower B♭ | Lower D♭ | Lower E♭ | Lower G♭ | Lower A♭ | Higher B♭ | Higher D♭ | |||
These tones are not arranged in order or in a scale, as one would think, but are a bit more arbitrarily placed. It is possible to play the intro to Calamari Inkantation(NA/EU/OC)[a] / シオカラ節(JP)[b] by moving the cursor between numbers in a specific pattern, which might explain the way the notes are arranged.
The pattern is as follows, each row corresponding to a bar of music:
7 6 7 6 7 6 7 6 5 6 7 6 7 6 7 2 3 8 7 6 7 6 7 6 7 6 5 6 7 2 3 8 3 2 7 2 3 8 9 8 3 2 7 6 7
Sunken Scroll flipbook
Each Sunken Scroll has a doodle of a Character on the bottom right corner. By flipping through the pages, one can see a flipbook-like animation showing the character flip around twice and turn into different ones. It starts off with the Zapfish, then changes to Judd, and finally, to Sheldon.
Squid Sister wave
To the left of the Dojo on Inkopolis Plaza, there is a studio where the Squid Sisters can be found chatting. By staying near the window, the sisters will eventually wave at the player. Using the first person view with 
allows one to zoom in on the scene.
Dumpster Zapfish
There is a stuffed Zapfish in the open dumpster behind Cap'n Cuttlefish's manhole in Inkopolis Plaza. Stuffed Zapfishes are used when the real Zapfish for the level has already been collected by Agent 3.
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