and im on ps3, easter egg is teh same, just if anyone is gonna do it. make sure you understand the majhong tiles. There are four that are for north,east,south,west. then there is 1 bamboo,2 bamboo, 3 bamboo and 4 bamboo. You will need to find all of them. once you find them they are color matched to direction to #. these tiles are small like the nav card small.
And The small boss crawler things, if you only knife them, when you get the max ammo you will recieve a free perk