Continuity mistake: In the scene where Bunny kills the one legged Vietnamese with the butt of his rifle, watch the cigarette in Sgt. O'Neill's mouth. In a shot after the kid is dead, the cigarette in O'Neill's mouth is short. When it shows him again, the cigarette has mysteriously grown.
Revealing mistake: When Charlie Sheen fires at the villagers' feet there are no shell casings being ejected from the weapon, and there is also no muzzle flash.
Continuity mistake: After the napalm has been dropped and Charlie Sheen is blackened from the fire (and others are dead and burned), the vegetation is all still green and unscathed. Shouldn't that also be burned and destroyed from the napalm?
Deliberate mistake: Throughout the entire movie, every time Charlie Sheen is not wearing his helmet, especially when he's out in the field in this tropical climate, his hair is always meticulously combed back, blow-dried and puffy. As a veteran, I know from personal experience that when you take your helmet off, especially in a climate like that, the reality is your hair will be messy, sweaty, pressed flat and most unattractive.
Visible crew/equipment: In the sequence where Sgt Elias is charging the VC with his M16 (near when he dies) there is a shot when the camera rolls through the jungle and you can see a cameraman behind a tree.
Continuity mistake: In one scene as they are walking towards a village a shot shows them walking next to a river. Whilst it is meant to be raining and the troops are wearing raincoats have a look at the river. There is no splashing as droplets land, indicating that it wasn't raining at that particular moment. The rain was merely water sprayed in front of the camera.
Factual error: At the end of the film in a scene when company Bravo is defending after a VC attack the company commander (Dale Dye) is wearing Y-type pistol belt suspenders, which were not introduced until 1974.
Continuity mistake: After the final battle at the end of the film, there is a scene where Francis who was in the hole with Taylor during the final battle, stabs himself in his right thigh so that he will be injured for the second time and sent out. In a scene shortly there after we see Francis loaded onto a helicopter and the bandage is on his left thigh and not the right one where he stabbed himself.
Visible crew/equipment: When Elias is doing his famous run, watch his left hand. You can see he is holding the device used to set of the squibs. You can also make out a wire running up his arm.
Revealing mistake: During the fight scene in the village between Elias and Barnes, as they roll around on the ground, Barnes "hits" Elias with a right hook and Elias's head is thrown to the side as if he just caught a serious blow. The problem is Barnes's fist quite obviously clears the front of Elias's face by at least 5-6 inches.
Visible crew/equipment: In the scene where Charlie Sheen drags out the full barrels from the lavatory a microphone drops down from the top of the picture frame
Factual error: Several distinct loon calls are added in the background for about 30 seconds, along with the pipes and other bird calls. Loons are native to Northern America only, and don't exist in Southeast Asia.
Continuity mistake: In the scene where Tom Berenger is near death and dares Charlie Sheen to shoot him, the first time Sgt. Barnes turns over on his back to face Sheen, his T-shirt is in pretty presentable shape. A few frames later when we see the good Sergeant his T-shirt is ripped and shredded.
Factual error: Bunny bites an aluminum beer can in half. Beer cans weren't aluminum until the mid 70s. He would have hurt his mouth on that one.
Character mistake: When the soldiers are emtying the latrines and the "surfer" guy says he "broke a hundred the other day" and has 92 days left, he states that April 17th is his DEROS (Date Eligible to Return from Overseas). Later we hear Charlie Sheen say that it's "New Years Day." This would have put the "Latrine scene" around January 5th.
Revealing mistake: At the end of the movie when the camp is being overrun, a U.S. soldier is standing to the left of a bunker, with his back to the camera, when he is shot. As he falls backwards he can be seen reaching up with both hands to throw his helmet up and out to simulate the effect of him being thrown backward by the force of the shot.
Continuity mistake: Bunny carries a shotgun throughout the entire film. In the final big battle scene, Bunny is seen firing his shotgun at the enemy while Junior cowers in the fox hole. When Junior runs out of the hole and Bunny turns around to yell at him, Bunny is suddenly holding an M-16 rifle. The scene cuts to Junior smacking into a tree and then quickly cuts back to Bunny, who is now holding his shotgun. As Bunny begins to turn toward the enemy, he still has shotgun in hand. When Bunny completes the turn and is shot by the NVA soldier, he is again holding the M-16.