Continuity mistake: When they leave the Do Lung Bridge the flag is visible on the roof of the boat, but several seconds later at the beginning of the next scene, it's gone. (01:48:45)
Audio problem: After leaving the Do Lung Bridge Chef hands out the mail to Clean who says, "Is that it?" If you look closely at Clean's lips he also says, "Thanks," which was edited out. (01:49:30)
Factual error: The date on the top of Chef's letter from Eva says, "Sept" with the year conveniently whited out. If the letter was written in September of 1969 she couldn't have known about Manson who wasn't arrested until December 3, 1969. This also dates the movie as taking place sometime in 1970. (01:50:50)
Continuity mistake: As they all read their mail from home Lance ignites a canister of purple smoke and it's sunset. In the next shot of Clean grabbing his tape recorder it's the afternoon and the sun isn't even shining. (01:50:55)
Continuity mistake: As Clean says, "I gotta tape from my mom," we see a rope tied around the cleat on the starboard side of the boat. He doesn't go near the cleat as he listens to the tape but the next time we see this spot, right when the attacks starts, the rope is gone. (01:51:00)
Continuity mistake: When Clean sits down in the back of the boat and opens up the tape from his mom, notice the order of the bullets in the machine gun to the right of the screen. When we first see them they're all packed in order, three shots later as he reads the letter they're uneven though no one has touched them. (01:51:00)
Other mistake: Clean gets some tapes from his mom back home but if you look closely at the back of his tape recorder as he grabs it there's no way for him to play the tapes without batteries in it. (01:51:00)
Continuity mistake: When he first opens the package from his mom Clean is holding a brown envelope with a cassette tape in it. Three shots later as he reads the letter from his mom and listens to the tape, the package has changed to a white carton. (01:51:05)
Continuity mistake: After leaving the Do Lung Bridge everyone sits around reading their mail from home. Lance takes the canister of purple smoke and proceeds to throw it overboard as he says, "Hot potato. Hot potato." In the next shot he has the canister in his hand again. (01:51:15)
Continuity mistake: As they all sit on the boat and read their letters from home Lance dances around with the purple smoke canister. Look closely as the red Vietnamese banner on the shoreline disappears between shots. (01:51:20)
Continuity mistake: As Lance dances around with the purple smoke canister there's nothing in front of the helm of the boat under the radar dome. Later as the rocket attack that kills Clean starts a helmet appears there. (01:51:30)
Continuity mistake: As Chef and Clean sit on the back of the PBR reading their mail, we see Lieutenant Kilgore's surfboard wedged between the machine guns. It's there until the shot when we see Clean after he's been killed, where it disappears. (01:51:40)
Continuity mistake: Just as the rocket attack starts on the boat Chef is reading his mail and says, "hey Lance ". Look closely at the bullets on the machine gun right behind him, they're all draped to the left of the gun, no one has touched them but in a previous shot they were draped to the right the gun. The M-16 has also been moved. (01:51:40)
Continuity mistake: Just after the rocket attack that kills Clean starts there's a close-up of Lance manning the machine gun in the front of the boat. The Vietnamese spray this area with machine gun fire and chip away a lot of the green paint to his left under the radar dome. The next time we see this spot the paint is untouched. (01:52:00)
Continuity mistake: Several different boats are used in this movie as "PBR Street Gang" and they are almost duplicates of each other. In the scene where Clean is killed look at the handrail on the port side that extends from the rear of the roof towards the front of the boat. The last section is kinked up at a 45-degree angle where it's attached to the roof. Two minutes later we see a wide shot of a different PBR which has a gentle bend in this piece of metal rather than the abrupt bend on the other boat. (01:52:00 - 01:54:05)
Visible crew/equipment: After Clean is killed in the rocket attack there are several shots where the camera crew films the front of the PBR as it approaches them. The spray and turbulence from their boat in front of the PBR can be seen in all of these shots. (01:52:20)
Continuity mistake: There's a pole stored on the port side of the PBR. It's behind Chef after we see Clean's dead body. It's been removed in the next scene when they arrive at the French plantation. This pole has been used before in the movie and is stored in this spot and if it were somewhere else on the boat we would see it. (01:52:25 - 01:55:30)
Continuity mistake: After the rocket attack Chief Phillips looks back and says, "Chef, Chef check out Clean. Captain, he's hit". Look closely at the blood spatter on that the piece of metal that was behind him during the attack. Later as Lance takes over the helm of the boat there's less blood dripping on it. (01:52:30)
Continuity mistake: After Clean is killed, the blood splatter on the PBR's metal plate changes. (01:52:34 - 01:52:58)
Continuity mistake: The red wind spinner in front of the helm of the PBR appears for the first time after the attack that killed Clean than disappears in the French Plantation scene (redux version). (01:54:00 - 01:57:40)
Chosen answer: Kurtz was protected by political connections and his military record from being relieved of command, and the Montagnard people whose village he was in were considered American allies, so they couldn't just send a force in to kill him or relieve him of command, but an individual assassin. (The US Government's "official" policy is that they do not engage in assassination, which is why "this mission does not exist, nor will it ever exist").
Captain Defenestrator