In 2014, developer Danny Gray revealed while promoting Monument Valley at its release that there was a single Easter egg hidden in the main game. It would eventually be discovered and then confirmed by Gray two years later that this secret was in the green room of the main game's final level X. Observatory, where a green model of an Arwing from the first Star Fox game can be found floating near some debris in the bottom-right corner of the area.

At the very beginning of Appendix v. The Lost Falls, after Ida presses the first switch in the level to raise the pillar the Totem is on up to where she is, a set of symbols carved into two sides of the pillar are revealed. These symbols are part of the ancient Zuish language from the game Fez, but they are used incorrectly in order to fit the message on the pillar (i.e. vertical spelling, no use of spaces, line breaks in the middle of words). When translated, it spells out this message:


This not only acts as a reference to the popular quote at the start of The Legend of Zelda to show Ida receiving help, but also acts as foreshadowing to the end of the level where Spoiler:the Totem is destroyed by a crushing stone pillar while helping Ida get past it, forcing her to go through the rest of the Forgotten Shores levels on her own.