Task Force 141 Soldier: "Surely you can't be serious."
Ghost: "I am serious. And don't call me Shirley."
Aliens a ton of them in the freighter level: "I like to keep this for close encounters." "Check those corners!" "We - are - leaving!"
Price gets back at it in 2. "Whatever you're going to do, Soap, do it fast!"
A Ranger over the radio in "From Their Own Accord" also goes "We - are - leaving!"
While he never quotes him verbatim, pretty much everything Dunn says after the EMP could be taken right out of Hudson's mouth.
While the heartbeat sensor is ostensibly a Rainbow Six reference (see below), the way it actually works has more in common with Alien's motion tracker.
Apocalypse Now - A level named "Charlie Don't Surf" during a helicopter assault.
Behind Enemy Lines - Zakhaev's son wears a track suit almost identical to the one worn by Sasha.
Black Hawk Down - Modern Warfare has you landing to rescue a downed helo pilot in an obvious Black Hawk Down reference. In 2, you are briefly trapped in a downed helo, and for that time re-enact the Shughart/Gordon scene from the same movie, complete with a "last magazine." Fortunately it doesn't end the same way.
Plus, every single helicopter, no matter how it's shot, will go down the exact same way that Super 61 did.
Modern Warfare 3 has you and your highly trained special-forces friends visiting Somalia to get some information out of the local warlord. Another of your friends pilots a helicopter as support. It gets shot down, and then you have to rescue the pilot.
Sandman, the Delta sergeant himself, is a walking reference to Black Hawk Down, being voiced by William Fichtner.
When told that police help is five minutes away, Wallcroft responds that "nothing takes five minutes!"
The multiplayer map "Bakaara" is a recreation of the first Blackhawk crash site.
Children of Men - The Prague level in the third game has a sequence which is heavily similar to this movie's apartment scene during the uprising.
Collateral - At the beginning of Takedown, the main villain waxes two NPCs in a re-enactment of the "Hey homie, is that my briefcase?" scene.
Counter-Strike - In Modern Warfare 3, the S.A.S. and G.I.G.N. special forces appear exactly like their depictions from Counter-Strike (notable because this depiction is not necessarily reflective of their real-life appearance, especially in the case of the S.A.S., due to variances in equipment loadout and battle dress uniforms)
Dr. Strangelove - A level named "No Fighting In The War Room" in Call of Duty 4.
Fallout 3 - MW2's damaged Washington Monument recalls the one in this game; both have exposed metal reinforcing rods, while the real monument is solid stone.
Generation Kill - The level in MW2 where you control the gun of a humvee is very similar to the end of the second episode, when the Marines of First Recon were shown being ambushed after leaving Nasiriyah. The sudden prevalence of the Military Alphabet compared to the first game, where no one ever even said "Oscar Mike," could be attributed to Generation Kill as well.
And the fact that every enemy infantryman is a "foot mobile."
Not to mention the Rangers' Humvees bearing a striking resemblance to the 1st Recon's "Ghetto Hoopties" right down to the "B[/]" identifier marking and the custom paint job the marines added themselves before the invasion.
Lethal Weapon: Shepherd's group is called "Shadow Company". The antagonists in the first Lethal Weapon were also called "Shadow Company".
Mass Effect - Shepherd is voiced by Lance Henriksen and is your overarching commander. Foley is voiced by Keith David and is your direct superior in the American campaign. With names, voices, and roles like that, it's too big to be a coincidence.
Night at the Museum - "An Evening with Infinity Ward", a bonus level that takes place in a museum, has most of the exhibits be real, live characters, although they only act out scenes from the missions, reminiscent of Night at the Museum. Pressing a button at the main desk will cause all of those said exhibits to stop being docile and attack you.
Pulp Fiction - One of the achievements in Modern Warfare 2 is called "Royale With Cheese".
In the first Modern Warfare, during "Crew Expendable" if the player strays too far from Price in the first cargo bay, a mook will leap out with a goddamn Hand Cannon and ambush you while screaming, pretty much exactly like the last of Brett's gang did in the movie. Making it better is that surviving the ambush is very hard - in fact, almost a miracle.
Red Dawn (1984) - One of the missions in Modern Warfare 2 is titled "Wolverines!". The achievement for beating the level on Veteran is "Red Dawn", as well.
Rainbow Six - The heartbeat sensor is a fictional device that first appeared in the Rainbow Six novel and video games. Also, Task Force 141 is very similar to Team RAINBOW in that they are both multinational teams of badass special forces soldiers.
Rambo - In the Modern Warfare 3 mission "Back On The Grid" there is a part where you commandeer a .50 caliber machine gun mounted on a technical and use it to mow down waves of enemies. This mirrors a scene in the fourth Rambo movie.
The Rock - The shower room in the gulag is a recreation of a scene from the movie, and using green flares to avert an air strike during Whiskey Hotel references this movie as well.
It should be noted that Hans Zimmer did the music for both Modern Warfare 2 and The Rock, which adds a bit of depth to this particular shout-out.
Top Gun - A multiplayer title "Ghostrider", depicting a fighter plane.
Splinter Cell - In "The Only Easy Day... Was Yesterday", you have to infiltrate an oil rig, and can later acquire an F2000 assault rifle with a thermal scope. The title itself is a motto of the Navy SEALs.
STALKER: Shadow of Chernobyl - Obviously the main influence for the Chernobyl level in the first MW; the MW Chernobyl level visits many of the same locations, and as in STALKER the vehicle graveyards are shown to contain Mi-24 Hinds (the real ones don't).
Super Mario Bros. - The emblem reward for getting ten kills in a row while having no killstreaks equipped (hence worth trying only for this) is an 8-bit image of Capt. Price that looks exactly like Mario's Super Mario Bros.. 1 sprite.
Terminator 2 - There is a certain scene in Modern Warfare with Sgt. Paul Jackson entering a playground that looks eerily similar to the one seen in the dream sequence of Terminator 2.
The Winchester 1887 shotgun is a reference to Terminator 2, being Arnie's choice of gun for half the film; the gun in the game is a replica of the T2 prop, including having an enlarged lever for easier spin-cocking. Going Guns Akimbo with them results in the character working the lever action by flipping the whole gun around on his finger like Arnie did. The Modern Warfare 3 version has a standard-sized lever, but now also has "Hasta La Vista" engraved into the hammer.
Transformers - An unlockable callsign title in Modern Warfare 2 is "Transformer" and depicts a Pave Low; it is unlocked for getting the game-winning kill by calling in a Pave Low as a killstreak reward (the challenge is also called "Transformer"). In the 2007 film, Blackout transformed into a Pave Low.
TRON - Calling in 5 Tactical Nukes (a killstreak reward earned by amassing a 25 kill streak) unlocks a title with a Tron Lines background and the text "End of Line", the MCP's Verbal Tic from the movie.
True Lies - Getting the game-winning kill with a Harrier unlocks the multiplayer title "True Liar"
Also, the Prestige challenge for Harrier kills is called "You're Fired", the Pre-Mortem One-Liner from the movie.
In Modern Warfare 2, the restaurants are thinly-veiled Bland-Name Product versions of Taco Bell, TGI Friday's, Starbucks and Burger King.
In the training mission for Modern Warfare 1, you melee a watermelon, probably a reference to R. Lee Ermey's hate of watermelons.
In-series example; doesn't the attack on Whiskey Hotel seem a little familiar to storming the Reichstag in previous installments?
Another in-series example: one of the randomly-generated FSO agents in the MW3 level "Turbulence" is named Dmitri Petrenko - except for one missing letter, the exact same name as the Russian player character of World at War.
There was almost always a Loyalist soldier also named Dmitri Petrenko in Cal of Duty 4, and this was before World at War.