Factual error: When the US & Soviet navies attack the mutants on the beach they fire a large volley of surface to surface missiles. This is supposed to be 1962, the Cuban Missile Crisis, and ship launched surface to surface missiles had only just been introduced and weren't very common. But what makes this a technical error is that in the barrage we see RGM-84 Harpoon anti-ship missiles, introduced in 1977, and RGM-109 Tomahawk missiles (could be anti-ship or land attack) developed in the 70s and first entering service in 1983.MegaZone
Factual error: A Westland Bell 47G helicopter with the a registration of G-CHOP is seen to land at the Russian army camp/military headquarters when Charles, Magneto and the X-Men are approaching. The registration denotes it is a British aircraft, so unlikely to be in the middle of Russia, and this particular model was built in 1966 - four years after the Cuban missile crisisrwbthatisme
Factual error: When sitting in Xaviers mansion there are cushions on the sofas made from a Sanderson fabric, Dandelion Clocks, this fabric was designed in 2009 but the film is set in 1960.
Factual error: Miniskirts weren't in fashion until at least 1965-66, and the high rise hemlines worn by many female characters weren't around until '68 or '69.
Factual error: The Cuban Missile Crisis was in 1962. Rossiya Hotel (shown in the background of the Red Square overview) was built 1964-1967. (01:10:05)
Factual error: During the bar scene in Argentina, Magneto uses a dagger he took from one of the former SS Soldiers. It appears to be a Reichsarbeitsdienst dagger with the inscription "Blut und Ehre." This is incorrect as the inscription should read "Arbeit Adelt." "Blut und Ehre" was inscribed on Hitler youth knives as that was their motto.maximus92
Factual error: When Erik pulls the bullet out of Xavier's back, the bullet should be covered in blood, but it is completely dry.
Factual error: When the US government deliberates about blocking access to Cuba, they request the 7th fleet to be dispatched for the blockade. The 7th fleet is on the Pacific Ocean, not on the Atlantic. (01:47:00 - 01:48:00)
Factual error: There is a pinball machine in the lounge area of the CIA facility where the young mutants gather. The pinball machine's name is "Fun Land", it is a 1 player (1 at a time) machine made by D. Gottlieb and Company in 1968, and did not exist in the film's 1962 timeframe.