Early in the movie, when the babies are being chosen for the Adam program, armed guards can be seen in the nursery armed with M16-type rifles. The weapons are not seen clearly, but are most likely M16A2s.
M60 Machine Gun
During the training phase, several Humvees can be seen, each with an M60 machine gun mounted on the roof.
M4A1 Carbine
During the training phase, the child recruits can be seen firing 1st generation M4A1 Carbines fitted with C-More red dot sights and RIS foregrips.
Colt Single Action Army
The cruel and cowardly commander of the soldiers, Colonel Mekum (Jason Isaacs) can be seen carrying a nickel-plated Colt Single Action Army with pearl grips as his sidearm, using it to shoot first one of the older soldiers injured in the fight with Caine 607 (Jason Scott Lee), one of the newer soldiers, and then Captain Church (Gary Busey) when he refuses to follow orders.
Century Arms AK-47 Bullpup
The standard-issue assault rifles of the soldiers throughout the film, including Sergeant Todd (Kurt Russell) and later the super-soldiers, are modified Century Arms AK-47 bullpup rifles made to look futuristic. The weapons have been given extended barrels and shrouds that appear to have been borrowed from Franchi SPAS-12 shotguns. Additionally, the rifles have C-More red-dot sights, dual retractable bayonets, and tactical flashlights. In some scenes, the rifles feed from standard 30-round AK "banana"-style magazines (this is most obvious during a flashback when Sgt. Todd is seen reloading and his magazine is shown hitting the ground), while in other scenes, they are fitted with 100-round drum magazines.
Heckler & Koch HK91
During the "War of the Six Cities" flashback to Sgt. Todd's earlier days an enemy soldier is seen armed with a rifle which is definitely a Heckler & Koch G3 variant. It's not seen clearly, but looking closely, it is possible to see that that the rifle lacks the flipper magazine release of the original H&K G3, which means that it is almost certainly a civilian HK91 standing in for the mil-spec G3.
Heckler & Koch MP5A2
During the montage showing Sgt. Todd's service following his training, a combatant in the "Moscow Incident" can be seen brandishing a Heckler & Koch MP5A2 while holding a civilian woman hostage, Todd shooting both the enemy and the civilian with no regard for civilian casualties.
Franchi LF-57
During the flashback to the "Battle of the Argentine Moons", Sgt. Todd is using a pair of nickel-plated Franchi LF-57 submachine guns with the stocks removed and some type of old-fashioned tube sight installed on top.
Claridge LEC9
Todd and some of the settlers carry Claridge LEC9 Carbines - the long-barreled carbine version of the Claridge Hi-Tec S9. Though Goncz Armament, Inc. made a nearly identical carbine before Claridge did, the Goncz carbines were outfitted with wooden furniture, the Claridge carbines were sold with all black synthetic furniture, thus any carbine with black synthetic parts is assumed to be the Claridge variant.
MAK-90
One of the Arcadia 234 inhabitants can be seen with an MAK-90 rifle, the "post-ban" semi-automatic civilian version of the Chinese Norinco Type 56 (AK-47). It can be recognized by its thumbhole stock and full-circle front sight. Note that the rifle also seems to have a short 10-round magazine fitted.
Bushmaster XM15 "V-Match"
One of the Arcadia 234 inhabitants carries a Bushmaster XM15 "V-Match" semi-automatic rifle fitted with a C-More red-dot sight. It is not an M16A4 as mis-identified previously; the weapon's hand guards do not match those of any M16 variant, and the weapon also lacks a triangular front sight post, the most distinctive characteristic of the V-Match.
(Fake) DShK
The "Crawler" vehicles used by the soldiers during the attack on Arcadia 234 are armed with what appear to be turret-mounted DShK heavy machine guns, but these are actually dressed-up Browning M2HB machine guns.
Hand Held GE M134 Minigun
One of the soldiers engaged in the raid on the Arcadia 234 settlement can be seen firing a short-barreled hand held GE M134 Minigun. Sgt. Todd kills the soldier when his Minigun jam on him, then uses it when engaging the soldiers following the raid.
Heckler & Koch Mk 23 Mod 0
When Sgt. Todd assists in repelling the first wave of soldiers from the Arcadia 234 settlement, he can be seen picking up and loading a Heckler & Koch Mk 23 Mod 0 pistol.
Rocky Mountain Arms Patriot Pistol "Carbine"
While loading up to engage the soldiers after repelling the raid on the Arcadia 234 settlement, Sgt. Todd can be briefly seen with a pair of Patriot Pistols (which were common AR15 pistol variants around the same time as Olympic Arms' entry into the AR15 Pistol arena with their OA-93). These Patriot Pistols (which have a short AR barrel and flat top upper receiver), actually have the full length telescoping stock for the XM177/CAR15 carbines attached. It looks to be the same Patriot Upper mated to a full auto SP1 lower that was used in the movie Congo. This firearms is outfitted with an under-mounted flashlight, a vintage red laser sight (from the 1980s), and a Beta-C magazine.
Steyr SPP
While engaging the soldiers, Sgt. Todd takes a Steyr SPP converted to fire full-auto from one of the soldiers before dropping a grenade into one of the "Crawler" vehicles to kill the crew. The soldier inside the Crawler who gets killed is also brandishing an SPP. It would appear that the SPP is actually supposed to be the standard-issue sidearm for the Adam project soldiers; this is evidenced by the fact that during the flashback to the "Moscow Incident", all of the soldiers are carrying machine pistols on thigh holsters which appear to be SPPs.
Remington Rolling Block
One of the Arcadia 234 inhabitants can be seen carrying a Remington Rolling Block rifle, the ancient weapon apparently still in working order after centuries.
Tru Flite 37mm Super Long Range Gas Gun
A Tru Flite 37mm Super Long Range Gas Gun is seen on a man's back as Sgt. Todd walks over to pick up the Claridge LEC9. The Tru Flite 37nn Super Long Rage Gas Gun is a 37mm CS grenade launcher built by the Lake Erie Chemical Company.
Unknown Rifle?
I just watched this movie again today, and noticed that this gun wasn't on the page. It was seen during the town meeting when they discuss exiling Todd.
Unknown Rifles?
From the same scene, I also noticed these two rifles in the foreground. Can they be identified?
Flamethrowers
The genetically engineered soldiers use custom-built flamethrowers that were assembled specially for the movie.