Soldiers of the 1st Platoon, Bravo Company, 25th Infantry Division "Tropic Lightning" use M16A1s, most commonly seen in the hands of PFC Chris Taylor (Charlie Sheen).
M16
Crawford (Chris Pedersen) is briefly seen using what appears to be an original M16 as it lacks a forward assist. It could also be an AR-15/SP1 rifle, but since he is not seen firing it, it is unknown.
Colt Model 653P
SGT Elias Grodin (Willem Dafoe), SSG Robert Barnes (Tom Berenger), and 1LT Wolfe (Mark Moses) are armed with Colt Model 653P carbine assault rifles, noted by their rounded forward assists an 14.5" barrels, as the 653Ps were 653 export models sent to the Philippines. It is anachronistic to see these rifles in the movie, as they were not used during the Vietnam war.
M1911A1
The M1911A1 is the standard sidearm for all of the NCOs and Officers in the film. It is most prominantly seen used by SGT Elias (Willem Dafoe) when he does tunnel rat duty and SSG Barnes (Tom Berenger) when he uses it to threaten a little girl in the Village to get her father to talk.
Throughout the film, several of the soldiers are seen carrying M60 machine guns while on patrol. No one is mainly listed using one more than another because in Vietnam, sooner or later, everyone had to lug the 23lb Pig around on patrol.
B-40 RPG
Several NVA soldiers are armed with B-40 RPG's, a Vietnamese copy of the RPG-2.
Norinco Type 56
The Norinco Type 56 is the weapon of choice of the Vietnamese troops, many of which feature "pig-sticker" under folder bayonets. They are noted as Chinese Type 56 rifles based on their hooded front sights. Only the milled receiver variant of this rifle was actually used during the war. Towards the end of the film, both SSG Robert Barnes (Tom Berenger) and PFC Chris Taylor (Charlie Sheen) are seen using these rifles, picked up from dead Vietnamese soldiers.
M79 grenade launcher
The M79 grenade launcher is seen used by several soldiers during the film, including Tubbs, a member of Barnes' squad.
Browning M2HB
A Browning M2HB .50 cal is seen mounted on for use on an M113 Armored Personnel Carrier after the final stand.
I don't think that was a Nazi flag. If I remember correctly it was the Confederate "Stars and Bars". Charon68
An M72 LAW is seen strapped on top of PFC Chris Taylor's (Charlie Sheen) pack. It is also seen used by Barnes during the final stand.
M34 White Phosphorous Grenade
Huffmeister (Robert 'Rock' Galotti) is seen throwing an M34 White Phosphorous grenade (also called "Willy Pete" - slang for White Phosphorous) in one of the rice wells during the raid of the village.SSG Barnes also uses an M34 Grenade to destroy one of the underground tunnels, this time yelling "Willie Pete!" when he throws the grenade.
M26 "Lemon" hand grenade
M26 "Lemon" hand grenades are seen several times as the standard issue grenade of the members of the 1st Platoon.