During the mission "Second Sun" a runner named Vaughn emerges from a building and gives your team instructions to get to Whiskey Hotel. Your team then enters the same building that Pvt. Vaughn just exited, finding it occupied by an entrenched Russian patrol. Either Vaughn somehow didn't encounter the Russians, he forgot to mention them.
In the cut scene in space you see the missile detonate over Washington DC. There are no clouds at all anywhere near the East coast, then later, from the ground you can see clouds in the sky as the sun is setting. later it begins raining and by the middle part of the mission it is raining quite hard. A storm of this magnitude would have been very easy to see from space.
In the mission "Second Sun", a massive EMP destroys all electronics in the East Coast of the United States. Yet several cars, traffic lights, and computers can still be seen working throughout the level.
At the end of the level "Wolverines". If you can protect the Turret gun from the roof of Nate's restaurant from getting destroyed and carry it to the convoy when they arrive to pick you up, you can get into the vehicle with the turret and it will pass thru solid steel. If you turn forward you can even make it float through the passenger in the front seat.
The atmospheric nuclear detonation that destroys the ISS would, in fact, not do so. The lack of atmosphere would almost totally nullify the usual heat and blast wave effects associated with a nuclear explosion.
In the battle for Washington DC, troops are shown maneuvering closely with M1A2 Abrams tanks. If the player is next to or in front of one when it fires, their ears are left ringing. In reality, there is a zone extending 45 degrees to the right and left of the main gun's muzzle out to 200 yards where the overpressure from firing is lethal to unprotected infantry.
In the Multiplayer version of the game, Semtex comes in the form of a grenade, where you pull a pin, throw, and it sticks to a surface. However, Semtex is actually a plastic brick explosive, similar, albeit more powerful, than C4.
Task Force 141 members have their nationality patches on their shoulders or webbing, whereas in real life no identification would be shown as part of SOPs. Likewise, Soap McTavish wouldn't have a mohawk haircut, as it is a strong visual indicator, and would make any urban covert scenarios almost impossible for him to be anonymous.
Captain Price goes aboard the Russian sub to launch a missile in the hope that an EMP would end the war. But a launch of this sort requires both the ships captain and first officer to enter classified codes and use both keys. No one person can launch a missile.
The MH-53 "Pavelow" helicopter which is featured throughout the game is actually U.S. Air Force's (USAF) version of the HH-53 series of heavy lift helicopters. The "Pavelow" was a super heavy lift helicopter used for combat search and rescue and special operations by the USAF. The MH-53 was retired from all active U.S. military service in 2008.
In the mission, the Gulag, the F-15s call "Fox Three" when firing AGM-88 HARM anti-radiation missiles. This is incorrect as "Fox Three" is the brevity code that indicates the launch of an active radar-guided missile, such as the AIM-120 AMRAAM. The correct code for a HARM missile launch would be "Magnum".
Makarov wants Russia convinced that the airport attack was acted purely by American terrorists, hence his men speaking only English and using US NATO weapons. Makarov is a well known terrorist, yet he does not wear a mask, nor do his men. The security cameras, and even potential survivors could have recognized him. Furthermore, Makarov did lose one of his men in the attack, who could have been identified as a Russian. Furthermore, Pvt Allen could have killed them in the airport right before or during the massacre.
The goof item below may give away important plot points.
If a nuclear Intercontinental Ballistic Missile was air-burst (that is, detonated in the atmosphere instead of on land) relatively low over the East Coast, the electromagnetic pulse would wipe out all power and circuitry in all of the US, and probably parts of Canada and Mexico. And, since the missile could be seen air-bursting in space, it was detonated much higher in the atmosphere, which means the EMP would have wiped out most, if not all, of the power and circuitry in at least the entirety of North America, and probably other continents.
At the very end of the Game in your first fight with Shepherd he stabs you with a long handled knife which he leaves buried in your chest. After Peirce knocks his gun away you drag yourself along the ground on your belly in an attempt to get to the gun. After that fails you are again laying on your back with the knife still in your chest. It would not have been possible to roll onto your belly and move like that with the knife in your chest.