The Colt Anaconda can be found in a hidden spot in the last level of the game.
Desert Eagle Mark XIX
The Desert Eagle Mark XIX is available 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 variant, as evidenced by the lack of a fluted barrel.
Glock 17
The Glock 17 appears in the game, available as a starting weapon in several missions.
Submachine Guns
Heckler & Koch MP5SD3
The H&K MP5SD3 appears with an overloaded 32-round capacity (which, in reality, would make reloading more difficult).
IMI Uzi
The Uzi commonly appears in enemy hands; a dual-wielded version can be found as well. It has a much higher rate of fire than an actual Uzi, at 900 RPM (close the Mini Uzi variant's 950 RPM fire rate) versus the real 600.
Shotguns
Franchi SPAS-12
The Franchi SPAS-12 can be found in enemy hands; it is only used in pump-action mode.
Pancor Jackhammer
The Pancor Jackhammer can be found in the game (unrealistic, seeing as only two full-auto prototypes were ever made), with an incorrect 12-round cylinder instead of 10.
Assault Rifles
Colt XM177E2
The "M16A2" in the game is actually a Colt XM177E2 with an M16-style stock; it is equipped with an M203 grenade launcher. It fires fully-automatically, correct for the XM177E2, but incorrect for the M16A2, which fires in 3-round burst mode in reality.
Norinco Type 56
The Norinco Type 56 is the most commonly found weapon in the game, erroneously referred to as the original AK-47. It has an incorrect 32-round magazine instead of 30, and is modeled with a left-handed charging handle.
Sniper Rifles
Hybrid SVD Dragunov / FPK/PSL
The Dragunov in-game is actually a hybrid of the SVD Dragunov and the Romanian FPK/PSL. The weapon is silenced in-game, despite the model not featuring a suppressor visually.
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 belt box.
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.