Audio problem: We hear an over-dub of Playmate of the Year Carrie Foster shooting her cap guns three times. But if you look closely there's smoke only the first two times and the third time she doesn't actually pull the trigger. (01:08:40)
Continuity mistake: When the bunnies are dancing there's a close up of playmate Sandra Beatty and as a soldier yells, "take it off" it's raining. In the next shot it's not. (01:09:10)
Continuity mistake: When the soldiers crash the stage the pink "Playmate of the Year" sign in the back is moving from the wind and then stationary between shots. (01:09:30)
Continuity mistake: As the soldiers crash the stage the two rifles that the playmates were using in their dance have disappeared from the stage. (01:09:40)
Other mistake: Soldiers are already crashing the stage as Bill Graham gets the helicopter crew to rev up the engines but the two Green Beret security guards that are watching the girls have quite a delayed reaction and act as if nothings happening at all. (01:09:40)
Continuity mistake: As the soldiers crash the stage, Playmate Carrie Foster signs one of her pictures on a soldier's back as he leans over. In the next shot she signs it again. (01:09:40)
Continuity mistake: After the soldiers crash the stage Miss May goes from having no-one around her to having a bunch of soldiers surrounding her between shots. (01:09:45)
Continuity mistake: As the soldiers crash the stage Bill Graham ignites the smoke canister and the flashing green running lights above and under the left door of the helicopter are off. In the next shot, as he gets in, they're on. (01:09:55)
Continuity mistake: Just before they leave the USO show the helicopter pilot on the left goes from looking at the controls to looking at the camera between shots. (01:10:10)
Continuity mistake: As they leave the USO show the Green Beret security guard gets into the helicopter before Bill Graham. In the next shot he gets in again. (01:10:10)
Audio problem: As he leaves the USO show Bill Graham ignites a smoke canister before he gets into the helicopter and says, "So long," but his lips indicate that he's just whistling. (01:10:10)
Visible crew/equipment: Just before the Playboy helicopter leaves the USO show there's a shot of the stage from behind the audience and you can see the shadow of the cameramen moving from left to right on the shirts of the soldiers. (01:10:15)
Visible crew/equipment: Just before the Playboy helicopter takes off from the stage the first stuntman who hangs off the skid runs up, taps on the window to signal the pilot, then reaches down for several seconds as he attaches a cable to himself. You can see the second stuntman as he holds onto this cable with his right hand when he pulls the first stuntman's pants down. (01:10:20)
Continuity mistake: The next day as the boat leaves the USO show at Hau Phat to continue up the river we see the battered stage from the back of the boat. The boat passes the stage by about 100 feet but in the next shot its back right next to the stage. (01:11:25)
Continuity mistake: The day after the USO show at Hau Phat, the boat leaves and there are five men working on the stage. In the next shot there are three. (01:11:35)
Continuity mistake: As the boat leaves the USO show at Hau Phat Captain Willard says, "The war was being run by a bunch of four star clowns who were gonna end up giving the whole circus away". He says this as he walks to the back of the boat moving the 60 caliber machine gun on his way so that is faces frontward. In the next shot it's been moved and is now facing sideways. (01:11:40)
Continuity mistake: As Chef shows Chief Phillips and Clean the picture in his Playboy magazine of Miss December you can see the USO stage behind them. In the previous shot of the boat leaving one of the six tall lipstick statues on the upper left of the grandstand was knocked down. Now as the boat departs all six statues are standing. (01:11:50)
Continuity mistake: As they depart from the USO show at Hau Phat Chef shows everyone his picture of Miss December and there's a helmet hanging on a poll in the rear of the boat with the top facing Chief Phillips. Each time we see this helmet in the next few shots it moves sometimes facing the back of the boat and sometimes facing the front. (01:11:55)
Audio problem: We see and hear Chef rip the picture from his Playboy magazine of Miss December in half. In the next shot as he tapes it up behind Chief Phillips it's all in one piece. (01:12:05)
Continuity mistake: During Clean's story about a Vietnamese lieutenant Chef puts up his picture of Miss December behind Chief Phillips and its raining and his hat is wet. In the previous and next shot it's not raining. (01:12:15)
Answer: It's not any specific song; it's just the kind of generic piano music you'd hear at dinner at a high-class restaurant of the era. Think of scenes in movies, films, etc. set or made in the '50s and '60s, where the characters go to a nice dinner and there's someone at the piano playing unobtrusive music to accompany the food/conversation.