When Meadows takes his first bite of his first hot dog dipped in mustard, he opens his mouth - and his tongue is already stained bright yellow.
About 50 minutes into the movie, the trio are walking by Gate 4 at the train station. One of the Marines they are about to fight is walking ahead of them. Moments later, the same Marine and several others are walking behind them.
When Meadows is in the office waiting to leave for prison, the camera is focused on his shoes, which are all scuffed, but in later scenes his shoes are shined.
Badass & Mule take off their SP bands and white utility belts before brawling with the Marines in Penn Station NYC, and afterwards run off without them. Much later when leaving the Boston Hotel, they're wearing them again.
The MAA Master Chief is not wearing a Master-at-Arms rating badge, he is wearing a Boatswain mate rating badge.
The Master At Arms rating was disestablished in 1921, but was officially re-established on 1 August 1973. Therefore, as the story takes place, a Master Chief Boatswain's Mate being assigned the collateral duty of MAA is entirely accurate.
When they try to buy Meadows a beer in Washington DC, the bartender will not serve him because he is underage. It is later stated that Meadows is 18. The drinking age for beer in Washington DC has always been 18 since Prohibition ended. It was only raised to 21 in the 1980's.
Even though Meadows would have been out of Boot Camp for a comparatively short time, he still would've known not to address the MAA (an enlisted man) as "sir."
While at the ice skating rink Buddusky says of Meadows "Look at the size of this guy on roller skates."
In an exterior shot, the train traveling northeast from New York to Boston passes a water tower in Secaucus, New Jersey, west of New York.
Many of the actors playing Marines wear their hair too long. Additionaly, many sport sideburns. According to Marine Corps grooming regulations, sideburns will not extend below the top of the orifice of the ear.
In Nichiren Shoshu Buddhism, prayer beads include two strands which hang on the left hand and three strands on the right while chanting with palms pressed together. When Donna is seen in profile chanting for Meadows, her prayer beads appear opposite from the correct arrangement with three strands on the left hand.