Movie for the day: Platoon

War History Online has an article about the mistakes in Platoon:

Anachronisms
When the men are playing cards, one of the men is looking at a Playboy from March of 1971; the film took place in 1967.
Set in 1967, it features Bunny listening to Merle Haggard’s Okie from Muskogee, which wasn't released until 1969.
In the last battle, as well as in the patrol in the very beginning, Captain Harris was seen wearing nylon Y-shaped suspenders, which were not issued until the 1970s.
When the soldiers are celebrating in the tent early in the film, they are drinking Budweiser from two-piece stay-tab cans with UPC symbols. Container companies introduced the two-piece can in 1974, the stay-tab in 1975 and the UPC symbol in 1978. Budweiser introduced the can style used in the movie in 1981.
Staff Sergeant Barnes and Sergeant Elias both carry Cold Steel-brand knives, which were not manufactured until the 1980s.
When they board the UH-1 Huey near the church right before the scene where Sergeant Elias gets chased, a Philippine Air Force insignia can be seen on the tail boom of the helicopter. The PAF did not operate in Vietnam.
The “drug den” uses miniature Christmas lights, which didn't exist  in 1968.
Both Staff Sergeant Barnes and Sergeant Elias are seen carrying M16A2 rifles  with round hand grips and collapsible stocks. These rifles were not available until the early 1980s Staff Sergeant Barnes and Sergeant Elias use the Colt Model 653 which was not available until 1973.
During the ambush scene where Private Gardner shows Private Taylor a picture of his girl back home, the calendar in his wallet doesn’t match 1967. More than likely its a calendar from 1986, the year of production.
Boom mic visible
In right upper corner, when they are “emptying the shitter”.
It's visible above King’s head when he lights his cigarette.
Character error 
At one point, a character is warned not to drink from a river because he might get malaria. While drinking the water could cause any number of diseases, malaria is not one of them, as it can only be transmitted by insect bite.
The characters in the movie are in the Army, but on the cover, the dog tags that make up the two “O”s in Platoon read USMC.
When Taylor, King, and Crawford are cleaning the latrines, King says he has 39 days left to serve and will be released from duty in March, while Crawford says he has 92 and will be released on 17 April. With nearly 8 weeks separating their discharges and Crawford out on 17 April, King would be out in February, not March.
Continuity
When the platoon finds the bunker complex, the lieutenant sends Taylor and Washington out to guard the flank. Washington has a pack of Marlboros stuck in his helmet. Once he reaches his position, it is a pack of Kools in his helmet.
During the last battle, Sergeant O’Neill hides behind a dead body. As he pulls the body over him, the body’s eyes are closed but, when we see O’Neill peeking out, the eyes are open.
At the bunker complex, Sergeant Elias goes into the tunnels. In one shot he goes through some water but, in the following shots, he is dry.
When leaving the burning village, Staff Sergeant Barnes’ left eye is black. When he and Sgt. Elias return to base camp and have a discussion with the captain, Barnes’ right eye is black.
Staff Sergeant Barnes’ t-shirt when confronted by Chris at the end.After the first firefight, the blood the medic puts on Private Gardner’s forehead disappears.
When Bunny is in the tent talking to Junior, he opens his beer can with a “church key” (can opener). But when Lieutenant Wolfe walks in and Bunny bites a piece out of the can, it has a pop-top and shows no sign of having been opened with a “church key”.
The length on the soldier’s cigar when they are in the bunker looking at the Viet Cong maps, right before the booby trap blows.
The day after Sergeant Barnes cuts Private Taylor under his eye during the tent scene, neither a cut or scar is visible.
The position of the bandoliers worn by King in the goodbye scene with Chris just before the climactic battle.
After the last battle, Chris has obvious injuries to the face and arms, skin burns, etc. As he is stretchered out, his face and arms no longer have the blackened marks
In the third battle (when ambushed by the VC), the machine gunner (Morehouse) was hit by an artillery shell from friendly fire and was shattered into pieces by the explosion. When the troops evacuated, his quite complete body, although charred, was the first one taken out.
Crew or equipment visible 
During the opening credits, when the men are first hiking through the jungle, Big Harold slips and rolls down a hillside towards the camera. You can see the camera operator’s hand in the bottom right corner of the screen trying to stop the actor’s fall.
Errors in geography
When Sandy and Sal are investigating the bunker, they come across a reused ammo-box filled with maps. The map shown is actually of the British Isles with Ireland and most of England and northern France plainly visible. A local VC/NVA unit would have no interest in detailed maps of Europe.
Factual errors 
In the attack on the camp, we see two NVA/VC soldiers acting as suicide bombers (one falls and explodes, the other makes it into the communication bunker before blowing up). In the script, these two men are identified as sappers. NVA and VC sappers were specially trained combat engineers/reconnaissance commandos who used stealth to infiltrate a camp’s defenses and take out strategic targets, such as barbed wire obstacles or bunkers, with explosives before the main attack. Although there were reports of Viet Cong and North Vietnamese troops using suicide bombers during the war, sappers were never used as suicide bombers because they were considered too valuable to expend.
The uniformed VC/NVA troops are often depicted wearing steel helmets; steel helmets were only worn by NVA anti-aircraft troops protecting base camps in Cambodia, Laos, and North Vietnam. The VC/NVA troops ought to be wearing either floppy “boonie-hats” or the standard NVA sun helmet.
In the opening credits, the military technical advisor Captain Dale Dye is mistakenly credited as belonging to the Marine “Corp.” instead of “Corps”. The “US Marine Corps” is a military organization, not a corporation.
Taylor arrives in Vietnam wearing the unit insignia of the 25th Infantry Division. Low-ranking enlisted infantry replacements did not arrive in Vietnam with unit assignments, or insignia, but were assigned to line units as required.
Miscellaneous
One of the officers in the Battalion Command Post bunker that is suicide-bombed during the final battle, while he is initially surprised, seems strangely unconcerned otherwise when the bomber rushes inside.
Revealing mistakes
When the booby trapped device (the box with Vietcong maps) in the bunker explodes, it rips off the arms of one of the soldiers. When he stumbles out of the bunker and dies, his hands are clearly visible hanging out under his t-shirt.
As Chris is firing at the villagers feet in the hut, no fired shell casings are being ejected from the rifle, although we hear it firing.
While the troop are in the VC village, interrogating the villagers, searching for weapons, etc; it is obvious that their rifle bayonets are rubber.
When the M60 machine gun is being fired, the rounds on the ammo belt are clearly blanks; the ends of the cartridges are crimped and there are no bullets.
When we see Chris and the other new soldiers arriving in Vietnam during the opening sequence of the film, they jump to the ground from the rear end of an Air Force C-130; the rear ramp they would have walked down is missing. The ramp which doubles as the rear cargo door is either closed during long distance flights or partially open flying ‘in country’ with a rear gunner positioned out on the ramp tethered inside of the plane.
Some of Sergeant Barnes’ scars on his body can be seen partially peeling off.
When the men are wrestling through the foliage in a rainstorm near the beginning, the rain sounds like it has an echo, as if it were inside a stage.
During the scene where Chris (played by Charlie Sheen) gets his second taste of marijuana through the shotgun barrel handled by Elias (played by Willem Dafoe), Elias first racks the slide back and forwards, meaning the bolt is now closed. However, when Elias starts to blow smoke into the barrel the bolt is now at the back position and open. In order for Elias to truly use the shotgun to blow smoke through the barrel, the shotgun bolt would have to be at the open position, meaning the “back and forwards” slide of the shotgun in the beginning of the scene was a editing error.
When Elias kills the VC in the tunnel complex, he uses a 1911A1 pistol which requires the hammer to be cocked before it will fire. After he shoots and kills the VC, the hammer should still be in the cocked position yet the hammer is shown as being down. There would be no reason an experienced combat soldier like Elias would lower the hammer when he may have to fire again.
Continuity
We see a view from the helicopter of Elias running as he gets shot by the Vietcong and, during this shot, he raises his arms up, but when it goes to a closeup of him, his arms are suddenly down and then raised up as he dies.
After the final battle, Francis stabs himself in the right leg. He has a bandage on his left leg when seen on the evacuation helicopter.
During Bunny’s last stand he is seen carrying his shotgun, but in the next shot he is carrying an M16 just before he’s shot.
Crew or equipment visible
Exploding pack under Barnes’ t-shirt when Taylor shoots him.

Rico says it's easy to criticize, but hard to make a perfect movie... (Though some of these should have been caught by a smart filmmaker, or at least the editor...)