Revealing mistake: In the major helicopter scene when Ride of the Valkyries is played, the actual tape isn't going over the playing heads. (00:37:29)
Continuity mistake: After the helicopter attack when the chopper drops the patrol boat into the water, you can see the canopy and the radar type antenna break and collapse. When you see it again it's in perfect condition. (00:46:55)
Continuity mistake: As they pull up next to the Vietnamese sampan Clean runs to the port side of the boat in order to catch the tow rope. Chef is standing behind Captain Willard in middle of the boat and doesn't move and all. In the next shot Clean and Chef are both standing on the edge of the port side of the boat. (01:34:50)
Visible crew/equipment: As the boat crew steps ashore to find Kilgore, the obvious shadows of two crew and their equipment are seen moving across the backs of the soldiers and then the raised netting slightly further away. This isn't the documentary crew they meet shortly afterwards, who are further onto the mainland. (00:27:20)
Continuity mistake: As Chef grabs the black wig it's clear to see that the window on the helicopter door has a strain crack going down the middle of it. It's there for two shots then when Clean hammers on the helicopter door the first time it's not broken. After he climbs up onto the helicopter and bangs on the front windshield he comes back to the side window a second time and it's cracked again. (01:29:55)
Factual error: 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 of 6 choppers, not without an enormous speaker rig and the power to run it. They are using bog standard home stereo speakers, not the huge bullhorn speakers used later in the war to intimidate the enemy. 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.
Continuity mistake: Captain Willard and Lance run away from Lieutenant Col. Kilgore and the captain says, "get the f&% outta here". As this happens a helicopter is flying towards the colonel and two soldiers are helping an injured soldier. The camera cuts away for three seconds then back to a wide shot of the colonel again and the helicopter and the injured soldier have disappeared. (00:51:00)
Continuity mistake: When the captain realizes that Chef's head is in his lap he moves around violently trying to get it away from him. We can see that both his legs are tied up with wire but in the next close-up of Chef's head on the ground the captain's foot is freely moving around. (02:47:20)