Welp, I found a bug. A huge bug. Oh, and a small bug.
Small bug first, randomly, when scrolling screens in the overworld, I will be warped to a random screen in a solid place when the time of day transitions.
Big bug now. If you use the Switch Stone exactly when the screen transitions to another time (easily done by holding the item button), you will become invisible. To change back, you use the stone again. However, that's not the biggest thing about it. While in this state, you are invincible, meaning you can't be killed. You can even render yourself visible again while still keeping the invincibility by going to the final boss confrontation. By doing this, you can cheese everything in the game, including said final boss.
Also, Epsalon, there are about 1-2 fairies hidden behind trees in the overworld. I know for a fact there is one behind a tree on the beach in the west.