Easter eggs
From Inkipedia, the Splatoon wiki
The following is a list of Easter eggs and secrets in Splatoon.
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 and using the first person view with ZR, the sisters will eventually wave at the player.
Blooper and Octorok
Hidden in various areas such as Zone 4 are stickers featuring the Blooper from Super Mario Bros. and the Octorok from The Legend of Zelda and Zelda II: The Adventure of Link.
