Mugshot of the Boss of Crytek

When you are walking around the city in-game if you look for a Newstand on one of the magazines on the Newstand is a mugshot of the Boss of Crytek.

Meme Reference

As you are walking around the city look for the magazine stands, if you look closely one of the magazines that says the words "Simple" on it will have the popular "Raging" meme face on it, enjoy!

Back to the Future Reference

In the first level you have the ability to flank some CELL soldiers by entering a small sewer after the subway. You should find some electrical wires hanging above your head that say "Caution 1.21 Gigawatts." This is a reference the the movie trilogy.

Actual Easter Eggs

There's a small batch of color Easter Eggs in the mission Gate Keepers. Get into the building past the CELL checkpoint and you will be in the area where you can locate the Easter Eggs.

CELL Disco Party

In Dead Man Walking you will get an Objective called "Locate the Nanosuit Deep Scan Cradle; Locate Gould." Take the elevator down at the end of the level and go down the hallway. Take a right and look for a security camera and a bank of equipment. Hop the red rope and look for a switch. Hold ACTION to activate the switch and a red light will shine. Head back to the elevator and hop another red rope to reach a second elevator. The switch will be glowing. Hit ACTION again to open it and you will see a strange sight: A CELL disco party in the elevator!