Call of Duty 4 Modern Warfare Easter Egg - Airplane!

After clearing the game, watch through all of the credits and you will get to the special mile high club level called Epilogue.

For an intro you hear Cpt Price chatting to some SAS guy saying:
P: We're going in deep, and were going in hard.
SaS: Surely you can't be serious?
P: I am serious, and don't call me Shirley

This is a reference to the film Airplane! and this level is set on and aeroplane =D