During the introductory sequence, the fictional F/A-37 "Talon" fighter piloted by Lieutenant Kara Wade (Jessica Biel) is fired on by antiaircraft guns, including a 40mm Bofors gun in a single mount.
M61 Vulcan
M61 Vulcan cannons are presumably mounted on the various US fighters seen during the movie, but are also seen clearly; several appear in the introduction in M167 Vulcan Air Defence System (VADS) towed mountings, while others are visible in Phalanx installations on the the carrier USS Abraham Lincoln.
M16A2 Rifle
The M16A2 rifle is the standard weapon of US military personnel, most notably the US Marines on the Naval Vessels.
Beretta 92FS
The Beretta 92FS is the standard sidearm of US military personnel, standing in for the military M9.
Norinco Type 56
The Chinese AK/AKM variant, the Type 56 (and 56-1 the folding stock version) are the most commonly seen AK47/AKM rifle in movies and television (at least those done by U.S. Production companies). The Type 56 (full stock) version is commonly seen in the movie, usually in the hands of terrorists of many different stripes. Terrorist guards from several organizations are seen wielding the weapon in Rangoon, Islamic Extremists in a mountain fortress in Tajikistan, and North Korean Soldiers.
AK-47
In addition to the many Norinco Type 56 Chinese AK rifles, terrorists are also seen wielding what looks like original milled receiver AK-47 rifles with original front sights (not the hooded Type 56 sights). However, being how 'new' they look, they can be the third pattern AK-47 "Legend Series" rifles imported by Poly Technologies, Inc, between 1988-1989. Those were high end identical clones of the original AK-47 rifles but very few were imported.
Norinco Type 56 Target
Tajikistan terrorists are seen using a long barreled Type 56 variant rifle. It has an underfolding stock and a long barrel but no bipod.
SA Vz. 58
The SA Vz.58 assault rifle is carried by Tajikistan terrorists at the mountain fortress.
SKS Rifle
Carried by Tajikistan terrorists, they appear to be the Russian built SKS rifles with laminated stocks and full blade bayonets.
Heckler & Koch PDW (MP7 prototype)
A prototype Heckler & Koch MP7, the Heckler & Koch PDW, is carried and used by Lieutenant Kara Wade (Jessica Biel) when she is shot down over North Korean Territory.
Colt Model 733
Though the official Colt 733 was 11.5" we see 10" M16 short carbines, in the hands of covert ops thugs in Alaska.
At the mountain fortress, there are several gunners who are manning World War Two vintage Oerlikon 20mm Cannons.
SA-7 Launcher
SA-7 Grail surface to air missiles are fired at EDI and the other aircraft as they attack the mountain fortress.
SVD Dragunov
A North Korean marksman with the group tasked with tracking down one of the pilots uses an SVD Dragunov sniper rifle; another is later used by an officer at a border checkpoint.
Zastava M70AB2
A curious thing is that all the North Korean Troops carry the Yugo Zastava M70AB2 AK rifle (with a flashlight taped to the front hand guard).
A Black Steyr AUG is held by a black ops guard, Gannon tell him to set it on the ground. When Gannon is ambushed, the guard picks it up again, but is shot by Gannon. Steyr AUG rifles can also be seen in the Alaska Base Armory.
Colt M4 Carbine
An M4 Carbine is used by a guard to ambush Gannon. Also M4s are seen in the Alaska Base armory against the wall and being handed out to guys sent to kill Gannon.
M60 Machine Gun
An M60 machine gun is seen on the table of the Alaska Base Armory
Leader Dynamics T2 MK5
Leader Dynamics T2 MK5 assault rifles are seen in the Alaska Base Armory and being handed out to guys sent to kill Gannon.
L1A1 Self Loading Rifle
In the Alaska Base Armory, we also see Australian Wood stocked L1A1 SLRs against the wall and also being handed out.