The Desert Eagle Mark XIX in the game. Although depicted as the .357 Magnum model, shown by the use of .357 ammunition boxes and a 9-round magazine, the weapon model is actually that of the .50 AE, as evidenced by the lack of a fluted barrel.
The H&K MP5SD3 appears with an incorrect 32-round magazine instead of 30.
IMI Uzi
The Uzi appears in the game, and can be dual-wielded. It has a much higher rate of fire than an actual Uzi, 900 RPM versus the real 600 (though it is close to the Mini Uzi variant's 950 RPM).
Shotguns
Pancor Jackhammer
The Pancor Jackhammer appears with an incorrect 12-round magazine instead of 10.
The Norinco Type 56 appears in the game, erroneously referred to as the original AK-47, and with an incorrect 32-round magazine instead of 30. It also has an overwrought fire rate of 900 RPM instead of the real 600.
Colt XM177E2
The Colt XM177E2 appears with an M203 grenade launcher. It is erroneously referred to as the M16A2, and in-game it fires fully-automatically, correct for the XM177E2, but incorrect for the M16A2, which fires in 3-round burst mode in reality. It has a restricted fire rate of 600 RPM compared to the real weapon; a swap of fire rate between the XM177E2 and the Type 56 for the game would have been accurate.
Sniper Rifles
Hybrid Izhmash SVD Dragunov / FPK/PSL
The Dragunov in-game is actually a hybrid of the SVD Dragunov and the Romanian FPK/PSL. It is equipped with a suppressor.
Machine guns
Browning M2HB
The Browning M2HB is mounted in several places in the game.
FN Minimi
The FN Minimi appears in the game with a 100-round magazine.
Launchers
LAW 80
The LAW 80 appears in the game, and is incorrectly treated as reloadable. The player can hold a total of two rockets for it, and after being fired it is somewhat suddenly reloaded and ready to fire again.
M203
The M203 grenade launcher is attached to the Colt XM177E2. It is incorrectly reloaded by pumping it instead of opening the tube, loading a round and closing it.
Grenades
ALS T-470 Stun Grenade
The in-game "flashbang" is an ALS T-470 Stun Grenade.
C4
C4 explosives are used at scripted times, not as a standard weapon.