In the 4th chapter, (Zakarov's Penthouse) load up 'Penthouse View'.
When you begin, a helicopter will fly by the window. (Note: The egg is visible for very quickly here, but you can see it better in a few seconds.) Take out the side gunner of the vehicle,... more
In the Chicago Museum level a bit after the corridor fight with the S.W.A.T.-like members who drop in from the ceiling you'll be fighting through hallways. Eventually you'll take a right and see some boards with pictures on them - a few of them pirated-out.... more
(I found this in my PS3, but I think it has to be on the XBOX 360 game too)
In chapter one, you reach a market where there is an scene in which the character finds the envelope with the picture of the murdered cop and the 'White Rabbit'. After the scene,... more