The Battle of Polytopia contains four confirmed Easter Eggs. The difference between an Easter Egg and a bug is that Easter Eggs were added intentionally by the developer for players to find.
These Easter eggs are the Nature Bunny, the Rising Sun, the Luxidoor, and the floating/sinking city.
Nature Bunny EditTap ten times on any unoccupied square in your territory and you will spawn a Nature Bunny. The bunny moves randomly around the map, destroying any unit or building it touches. Nature Bunnies can be destroyed just like any other unit in the game. A Nature Bunny counts as an enemy unit in the sense that if one is on your city, you will not gain resources from it. The Nature Bunny can be used to your advantage if you have an unoccupied square of land that is separated from the land your city is on. It can also be used to remove unwanted buildings, however, with the addition of Destroy, it is not needed.
Sky/Rising Sun Edit
Originally teased in a post featuring a Hoodrick proverb, to do this Easter egg, touch and hold the sky for 20 seconds. Then, the sun will rise over the world. Touching and holding the sky for another 15 seconds will bring back the standard black sky, albeit without stars. Relaunching the app and resuming the game will restore the sky to default. This Easter Egg is only aesthetic and does not affect gameplay.
Luxidoor Easter Egg EditNormally, when you do not own a tribe, you don't get them in your game. The Luxidoor appear every once in a while to players who don't own the tribe. This can be considered an Easter Egg because they are not meant to be in the games. There is no known pattern as to in what settings it happens to your games. The developer, Midjiwan, has posted about this before, stating that they are merely "explorers" to our land.
Floating/Sinking City Easter Egg Edit
Alternately tap on the bottom left and bottom right tiles of a city. The city will either rise or sink lower. To get the city to float, start by tapping on the bottom left square. To get it to sink, start by tapping on the bottom right square. It will reset after training a unit or proceeding to the next turn. Similar to the Rising Sun, this Easter Egg is only aesthetic and does not affect gameplay. Enemies can still capture the city.