Kane And Lynch 2: Dog Days PC Cheats

Hitman reference
In Chapter 2 when you start to fight the police after you pass a bus, Kane tells you to enter the store to your left. Look at the pictures in that store to see Agent 47 from the Hitman series.

Mini Ninjas reference Play the "Subway" multiplayer level. When you spawn, turn to your left to find five signs. The first sign features the cast from Mini Ninjas.