When she is detailing her military experience Mason mentions she was "...embedded with MACV-SOG". The practice of embedding journalists with military units during wartime did not become a formal practice until the Iraq War of 2003. Prior to that many journalists during the Vietnam War, like Joe Galloway who was with the 7th Cavalry at the Ia Drang Valley, had to find their own way to the battlefield.
When Randa and Brooks go to get approval for the mission from Senator Willis, the computer terminals being used are Digital Equipment Corp VT100s. They didn't come into use/creation until the late 1978. The scene takes place in 1977 according to the time shown on the screen.
The establishing shot of the Athena shows a CH-47 Chinook helicopter on the bow, four UH-1 Hueys amidships, and one CH-53 Sea Stallion on the stern. In the helicopter battle with Kong later, at least 10 Hueys are shown.
The P-51 that crashes onto the island in 1944 had black and white stripes on its wings-these were known as "Invasion Stripes," and were used for a short period after the D-Day landings in Europe and not in the Pacific theater.
When she is detailing her military experience Mason mentions she was "...embedded with MACV-SOG". MACV-SOG stood for Military Assistance Command Vietnam-Special Operations/Studies and Observations Group. It was compromised of Vietnamese and American (largely Special Operations Forces like the Green Berets and SEALs) troops and was largely a joint operation with the CIA and concerned with largely behind the lines operations making it highly unlikely that a journalist, especially a female photojournalist, would be attached to them.
After the several helicopter crashes, the pilots are shown slogging through the jungle in regular infantry "steel pot" helmets and fatigues. Pilots don't carry "backup helmets" and they would have had only their flight helmet or maybe a rolled up cap in their flight suit. They don't bring infantry gear to change into in case they crash.
Although Northern Lights aren't visible in the southern hemisphere, they could have been seeing the Southern Lights. However, it is more likely that the lights and Skull Island's unique storm system are due to the 'hollow earth' characteristics which are never fully explained.
When Cole plans to sacrifice himself with the grenades he pulls the pins and releases the spoons. This sets the 5 second timed fuse. There were more than 5 seconds from arming to detonation, and the resulting explosion was way to large.
One pilot is shown carrying and using an AK-47. While this MAY have been acceptable on a combat mission in Vietnam, in a situation where there are no other troops similarly armed, it would be unacceptable and rather foolish. The shooter would be unable to either receive additional ammunition from a teammate in a crisis; nor would they be able to scrounge ammunition if they ran short.
The Japanese pilot was shown holding a German Mauser C96 pistol. Pilots of the Japanese Empire were not issued with this type of gun, as the Japanese Empire did not use this type of gun. German World War 2 pilots used this type of gun.
One of the helicopters is called a "Sea Stallion" which is the US Navy/USMC designation of the H-53 helicopter platform. The Army's version of this aircraft was nicknamed the "Jolly Green Giant". An Army officer in an aviation unit would NOT have made this mistake.
When Packard looks in his box of medals, there are a couple dog tags in there with black rubber "silencers" around their edges. These were used extensively in Vietnam to keep the two tags from rubbing together and creating noise. Yet later when the dead men's dog tags are collected, not a single one has a silencer.
The US insignia on the B-29 fuselage used for the makeshift boat is outlined in red. This particular insignia was used on US aircraft only for a short time during 1943. The B-29 did not enter service until 1944, so none would have had that insignia.
When Marlow describes the building of the boat, he says parts were taken from his P-51, the Japanese Zero, and a B-29 they found on the beach. But the twin machine guns on the bow were inside a Sperry ball turret, which was used on B-17s and B-24s but NOT B-29s. Also, the guns in a ball turret had special firing mechanisms for the turret operator and were not fired with traditional grip triggers as shown in the movie.
The deckhands launching the helicopters off the ship are wearing red jerseys and "cranials" which on board ship indicates they work either as firefighters or ordnancemen. The proper jersey color for launching aircraft would be yellow for an aircraft handler. The argument may be made that the ship was civilian not navy, but then none of the deck crew should have had on navy aircraft department gear at all.
The black and white photograph of the USS Lawton shown near the beginning of the film, shows the name of the ship painted on the bow. American warships have their names painted on the stern, not on the side of the bow.
Marlow said they scavenged parts from a crashed B-29 which explain the cockpit parts on the boat but the gun turret at the stern is from a ball turret like those found on a B-17. The B-29 did not have manned gun turrets except for the tail, they were remotely controlled from within the aircraft and so would not have had any Plexiglas like the turret used on the boat.
The boat that Marlow has constructed has an aircraft gun turret on the front. He says he constructed the boat mostly out of parts from a B-29 that had crashed on the island. The turret is a ball turret, a type which the B-29 did not use. The B-17 and the B-24, yes, but not the B-29.
The film depicts an anti-Vietnam War protest in 1973 and treats President Nixon's troop withdrawal announcement as a surprise. In fact, the Paris Accords had been signed in December 1972 and anti-war demonstrations petered out after Nixon accepted cease-fire terms the previous May. It was no secret to anyone in January 1973 that U.S. military involvement in Vietnam was over.
Mason was shown loading Kodak Plus-X film into her camera, which is, or was, a mid speed black and white film, OK for daytime shooting, but not for low light shots as she is seen taking later, at least not without camera shake and blurring or unless you use flash equipment. Also, as it is black and white, it isn't what you would use to capture the colors of the Southern Lights and a timed exposure would just be a bunch of gray blur. Many photographers carry more than one type of film and there may have been an off camera switch of film types.
The Japanese soldier was holding a German Mauser pistol. Although Japanese forces would not have been able to obtain additional munitions at the end of WWII due to financial issues, the munitions they already had would still be in circulation.