Mario Reference in Modern Warfare 2

[Berry]

In the Estate map, inside the cabin is a game console called the Gamestation, and one of the games lying around there has an interesting name which is called "Italian Plumber Princess Rescue" Which could most likely a Reference to Mario as he is a Italian Plumber and he does rescue Princess for a living.

[Equinox]

The cover also looks like a ton of piled up Goombas, dead ones perhaps?

[Sohakmet]

That doesn't make me like CoD a little bit. They don't even need to try.