One of the Guerrillas is seen holding a Colt Gold Cup National Match 1911 pistol on Cody (Danny McBride) when he flies a chopper to their Heroin base and Portnoy is seen armed with it before Tran kicks it out of his hand, implying it is a rubber prop.
Lazarus is seen using an M1911A1 as his sidearm in the film and uses it several times. Portnoy later gets his hands on it and uses it to hold Tran (Brandon Soo Hoo) hostage.
Tugg Speedman (Ben Stiller), along with various other characters, uses a 16" barreled AR-15 Sporter II Carbine throughout the film, which is anachronistic for Vietnam. The original AR-15 Carbine was an SP1 (sold between 1978-1985)), so there was no forward Assist on the upper receiver. Stiller's gun is the A1 version, or what Colt called the "Sporter II version" in U.S. sales. The Colt Model 653 based weapons came after 1973. He should be using an XM177 variation or the original AR-15 to be accurate to the era. It may be an homage to the movie Platoon since the characters of Barnes (Tom Berenger) and Elias (Willem Dafoe) used the Philippine export Colt Model 653 rifles. This film uses what is available in the United States, which happens to be the Sporter II carbine, since most of the movie was filmed in Los Angeles and Hawaii.
Kevin Sandusky (Jay Baruchel) and Alpo Chino (Brandon T. Jackson) both carry XM16E1 noted by their A1-style forward assists and three pronged flash hiders.
North Vietnamese soldiers are seen armed with AKM rifles during the opening "Hot LZ" scene, one of which most notably disembowels Sandsuky with his bayonet. In real life, it would be more accurate for the Vietnamese to use Soviet AK-47s or Chinese Type 56 rifles, the Chinese copy of the AK. An AKM at this time in history is an anachronism, Hanoi didn't get AKMs from the Soviet Union in any sort of numbers until 1972 and it would take at least a year for guns to filter down to the troops in the field. Even during the fall of Saigon in 1975 there are virtually no AKMs seen in wartime photographs of front line NVA units. At the point depicted in the movie within a movie, 99% of the guns in the field were Chinese Type 56s or vintage AK-47s. Later the guerrilla soldiers can be seen armed with AKM rifles, which appear to be Egyptian Maadi ARM rifles, one of the most common AKMs used in films.
Several guerrillas, including Tran (Brandon Soo Hoo) are armed with AKMSU carbines modified with Krinkov parts kits with side-folding stocks and black furniture to resemble AKS-74U carbines.
Three types of M4A1 carbines are seen used by the guerrilla forces, one of which is seen with the carry handle removed, Knights Armament RIS rails affixed (with no rail covers) and fitted with a Aimpoint red-dot sight, the other with the carry handle attached with an ACOG scope mounted on it. Lazarus grabs one of these rifles and is seen using it when searching for Speedman in the huts, however his does not have the ACOG sight.
One of the guerrillas is seen armed with an CQBR rifle with an A2 receiver, and an ACOG scope mounted on the carrying handle. The CQBR is a short 10.3in. barrel version of the M4A1 Carbine, so it certainly fits the profile.
Jeff "Fats" Portnoy (Jack Black) wields an M60 Machine Gun as his weapon in the film. Jack Black commented on how he got stuck with the M60, which he knew was nicknamed "The Pig", and was told he was a natural with it, something he found disturbing. Some other random soldiers are also seen firing M60s during the opening scene.
Tran uses a Norinco Type 69 antitank launcher to take out the truck the gang tries to escape in and tries to shoot down their chopper as they escape, the rocket being stopped only by a perfectly thrown TiVo box from Speedman's agent, Rick "Pecker" Peck (Matthew McConaughey).
Speedman and Portnoy are seen with M67 hand grenades attached to their belts and jackets. Since their film is supposed to take place in 1969, it makes sense to see them with these grenades, since '69 was when the M67 began to mass replace the M26 grenade.
Error creating thumbnail: File missingM67 hand grenade.Error creating thumbnail: File missingSpeedman keeps an M67 grenade hanging from his jacket.Error creating thumbnail: File missingSpeedman pulls the pin on his M67 grenade to throw at the enemy guerrillas, and despite it being a dummy grenade, Cody happens to set off some C4 at the same time. This is a common 'cliche' in action films, especially bad action films, which is why Speedman does it. In real life, one cannot pull the pin from a grenade with one's teeth without causing severe dental damage.Error creating thumbnail: File missingPortnoy keeps an M67 on his belt.
During the opening "Hot LZ" scene, a Vietnamese soldier tries to throw a Vietnam Era Chinese Type 67 Stick Grenade at the Huey chopper as it takes off, so Speedman jumps up and stops the grenade, losing his hands in the process. The "tin can" style Type 67 (also called the Type II) and the Pineapple style Type 58 stick grenades were commonly used by NVA (PAVN) soldiers or VC Guerrillas during the war.
Cody finds a M9 Flamethrower in the enemy shack. When he and Four Leaf Tayback (Nick Nolte) try to escape from the guerrilla's heroin base, Cody gives Tayback the Flamethrower, which he uses to hold back the enemies.
