Crowning Moment of Funny: The very last movie after the single-player campaign is over, in which Kennedy is negotiating an end to current hostilities, with Richard Nixon, Robert McNamara and Fidel Castro in attendance. You get that something's weird when Nixon gets all paranoid for some noises, then the team find themselves attacked... by zombies. Cue Kennedy revealing a Wall of Weapons, the presidents arming themselves, and proceeding to (presumably) kick zombie ass.
[Zombies break down the doors, flooding in The Pentagon]
Kennedy: [matter-of-factly] Zombies. Gentlemen, at times like these our capacity to retaliate must be and has to be massive, to deter all forms of aggression. Gentlemen [reveals the Wall of Weapons], lock and load!
The action shot has Nixon Dual Wielding assault rifles, desperately trying to look badass like the others.
Plenty of the characters' dialogue and one-liners can be hilarious:
Kennedy: I see an America unafraid of beauty and grace, but you beasts aren't helping! Kennedy: Stick that in your Warren Commission, dick!
"What's your name?" "Fuck you!" "When were you born?" "Kiss my ass!"
Made even better by the fact that it's Jake Gyllenhaal!
During Mason's meeting with President Kennedy, after Kennedy shows Mason a picture of Dragovich, he has a short vision of drawing his pistol and aiming it at Kennedy. Combination Crowning Moment of Funny and Nightmare Fuel.
When Reznov and company escape the boat while the British are attacking the Russians, we have this little conversation.
Reznov: This is not our war!
Reznov's Friend: Then who do we fight?
Hudson dramatically putting on his glasses at the end of "Revelations" gives a few chuckles to lighten up a rather dark moment.
Speaking of Hudson, his reactions to Woods and Bowman in SOG. Woods barely acknowledges him, to which he turns towards Mason and raises an eyebrow. After the mission, as he's trying to tell Woods and the newly-arrived Bowman about a possible defector, they walk off without listening; Hudson just trails off and shakes his head.
JFK's Zombies voice actor. Historically accurate or not, it's still funny. He sounds like Mayor Quimby from The Simpsons