Corrected entry: Unfortunately, the most striking scene in this - or any other - film is complete nonsense. During the helicopter attack they play "Ride of the Valkyries" on an ordinary tape deck through two smallish stereo speakers in order to scare the enemy prior to the attack. Okay, let's be clear - helicopters are LOUD. Very, very loud. The "enemy" would hear a flight of six helicopters approaching from thirty kilometers away. You simply could not play music loud enough to overcome the engine noise - not without an enormous speaker rig - and the power to run it. The music would be barely loud enough to be heard inside the helicopter, let alone outside it. This does not refer to the music playing on the film's soundtrack; Kilgore makes it clear he is playing music from the helicopter and he intends it to be heard by people on the ground.
Correction: In late 60s in Vietnam, "Psywar" Huey helicopters were equipped with very powerful horn-type loudspeakers that were used for agitation, crowd control and various announcements. Operation "Wandering Soul" at that time included choppers like the one shown in the music scene, playing back screams and agony of the wounded Vietnamese soldiers as well as advice to desert.
Corrected entry: There's a shot of a jet crashed in the mud on the shore of the Nung River in a classic scene as the PBR sails underneath it. This makes for a great shot and may be the way WWII airplanes crashed, but it's not the way B52's crash. At the rates of speed and high altitudes they fly a jet aiming down at the ground like that would be in a million pieces and not sticking up in the mud. Even if the tail section were blown off it wouldn't crash this way and that's why there are absolutely no pictures of a Viet Nam combat era B52's tail section that has crashed in this way.
Correction: The crash site wreckage you see is entirely typical of a low-level event such as an attempted emergency landing. The tail of an airliner or heavy bomber is often the only piece of piece of wreckage left after such an incident.
Corrected entry: Captain Willard says, "the VC knew his name by now and they were scared of him" as he marks his destination with an arrow on his map of the Vietnamese Cambodian border. The spot that he marks on this map is wrong because the boat follows the Nung River all the way to his destination at Kurtz' camp and there's no river anywhere near the spot he marks on this map.
Correction: When he marks the map, he is marking the trail of Kurtz, not his final destination.
Corrected entry: The Frenchmen with the accordion says, "Dien Bien Phu is a trap" but the closed captioning is wrong and reads "that serious".
Correction: That is a subtitling error, and not a mistake within the movie.
Corrected entry: As Captain Willard talks to the sergeant about getting some fuel he says, "I carry priority papers from Com-Sec intelligence II-Corp". "II-Corp" is left out in the closed captioning.
Correction: Subtitles often omit words if there are too many to fit on the screen; this is a subtitling choice, and is not a mistake.
Corrected entry: On the morning after the USO show, a helicopter is shown hovering above and behind the bleachers. The helicopter is an OH-58 Kiowa. This helicopter was not used in Vietnam during that time.
Correction: The OH-58A was first deployed to Vietnam in early Autumn 1969. The Kiowa operated with air cavalry, attack helicopter, and field artillery units. The OH-58A could also be configured as a troop transport, MedEvac, or for external lift missions using an external hook. Kiowas were commonly paired with the AH-1G Huey Cobra. The Kiowa would fly low to draw enemy fire, "trolling for fire, mark the target, and call in the Cobra to attack. (source: http://www.globalsecurity.org/military/systems/aircraft/oh-58a.htm).
Corrected entry: In northern South Vietnam (now central Vietnam), there are no navigable rivers that lead into Cambodia.
Correction: I don't recall, in all the times I've seen this movie, that they stated that they were on a river in central Vietnam. The Mekong Delta, to the south, most certainly goes into Cambodia.
Corrected entry: Willard is tearing the confidential mission paper into large pieces and throws them into the river. The pieces are large enough to reveal a lot of information or to be easily pieced together if picked up. The proper way to dispose of secret information would be to burn the pieces of paper.
Correction: True. But it's made clear several times that Willard isn't exactly the "model" officer. He probably knows full well they could be read, but couldn't care less.
Corrected entry: Willard is fully decked out with American gear and weaponry. This should not have been allowed; American personnel operating covertly in Laos and Cambodia were carefully re-equipped with enemy, untraceable, or foreign weapons (e.g. the Swedish K submachine gun) and clothing. If they were captured or killed, the USA could then deny any knowledge of these technically illegal missions - much harder to do if they're sporting an army-issue M16 and regulation clothing.
Correction: There are several possible explanations: The M-16 could belong to the PBR. But M-16s were very much in use also on covert operations. A Swedish submachine gun, as well as the sometimes used silenced Sten-gun, is as traceable to US forces as any American weapon. Willard's uniform is actually Cambodian, although widely used by US Special Forces.
Corrected entry: When the PBR arrives at the supply station during a torrential downpour, there are several dry gaps where no rain is falling - a dead giveaway of a rain machine.
Correction: It was real rain. This part of the film was nearly never made as the entire set was being washed away on a daily basis, as well as the cast and crew suffering all sorts of dirty water related illnesses. Tropical rain storms do sometimes appear as bombardments or torrents of water like this.
Corrected entry: During the scene where the PBR crew shoots up the Sampan, Clean's M-60 machine gun is loaded with blanks. The tips of the linked cartridges being fed into the gun are red, in other words not live rounds. It was mentioned that red tipped rounds are red 7.62 tracer rounds, but no ammo feed would consist entirely of tracers - they're only ever every 3 or 4 rounds.
Correction: The rounds in the scene are definitely blanks, but personally I spent many a night with my door gunner reconfiguring our M-60 door gun ammo belts to full tracer rounds.
Corrected entry: When the air cav attacks the village, one of the huts is flying a North Vietnamese flag, yet they are in South Vietnam, and the Viet Cong wouldn't be dumb enough to fly the 'enemy' flag where everyone can see it.
Correction: The village is a known Viet Cong fortress. Kilgore has already said that American boats are fired at every time they pass. Flying a North Vietnamese flag isn't telling the Americans anything they don't already know.