I have found easter eggs but i am not going to double post ones i don't want to but here are my favorite ones:

Music Easter Egg-There are 3 green glowing brain jars across the map. Two are right next to each other if you go through the left door when you spawn then go through the next door and go straight you will find two. The last one is in the small room next to one of the generators towards the right of the map (has type 100 in the room). Once all are activated it will play the song 'Beauty of Annhialation' from Treyarch's trailer.

5 Radio Recordings-First one is in spawning room and looks like a phone. When you spawn on the mainframe go down the stairs and go right and forward / like that forward slash. You will find a phone that when you press 'x' on it it talks about controlling the zombies and getting them to obey. Second one is in the teleporter room to the far left of the map (has MP40 in room). When you walk in go around the big objects in the room but not up the stairs. Behind them there is a radio message there. Third is in the room BEHIND the double tap machhine. If you walk through the door facing double tap and go to the left and forward you should see a phone on top of cabinets. Fourth is in the middle teleporter room with the STG-44. Walk in and go towards the teleporter and take a right down into the tunnel. Go to the end of the tunnel and behind the wall is a concealed phone with a message. The fifth on is also in that room but not in the tunnel. Once you walk in go towards the catwalk stairs and look on top of the cabinent. There is a radio with a message.

Hanging man-If you go to the far right teleporter room (Type 100 room) and go on the baclony look slightly to the left in a window and you will see his feet and if you shoot him with a ray gun he will fall down and restart the game.