Towards the end of Season Three, players noticed a small blue streak in the sky. Also, telescopes could be seen popping up on mountains or high places, presumably to observe the meteor. By the last week of the season, meteor pieces would fall from the sky, striking the ground, damaging players and destroying structures.

Rocket Launch

At the end of seson 4, there was a rocket that launched out of a mountain on the eastern side of the map. It flew all over the map, one of the boosters landed in Anarchy Acres . As it was flying, lasers came from the rocket and target Tilted Towers. As it flew down to tilted, a rift appeared and moved the rocket elsewhere. 

The Cube

Floating Island

Island/Cube Explosion