Factual error: In the scene where Xavier meets Raven, in 1944, one of the first shots shows a picture of Albert Einstein taken in 1947. (00:02:25)
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: 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: Erik arrives in Argentina at a place called Villa Gesell, shown to be a town in middle of mountains. Villa Gesell is a beach town on the Atlantic Ocean coast, with no mountains.
Factual error: The establishing shot of Shaw's boat says they're in Miami. Yet in the scene, we see a very large suspension bridge in the background. The bridge is the St Simons Bridge leading from Brunswick to St. Simons, Georgia.
Factual error: In the scene where they first pull up to the mutant research facility, they are in a 1972/3 Cadillac when the movie is set in 1962.
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.
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 crisis.
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: The aquarium in the lounge area of CIA facility where the young mutants gather has several blood parrot cichlids in it. This is a hybrid ornamental fish developed in Taiwan in the mid 1980s and did not exist in 1962.
Factual error: In one scene when Sebastian Shaw talks to Emma Frost in the submarine you can see the TV playing in the background, and right next to it is a Revox A-77 reel to reel machine. This movie is set in 1962, but Revox didn't introduce the A-77 until 1967.
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.
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.
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 scene at the beginning is set at a German concentration camp in occupied Poland in 1944 (as annotated). When Erik enters Shaw's office, the song "La Vie en Rose" by Edith Piaf is playing. The song wasn't written until 1945 and wasn't recorded until 1947.
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: The CIA is operating within the United States, given that they're not allowed to do so. Everything the CIA did in the film really should have been done by the FBI.
Answer: It is shown in X-Men: Days of Future Past that Hank made a serum that can help him walk.