Factual error: In the first scene where Dr Strange is preparing for surgery he uses improper surgical gowning technique breaking aseptic protocols. Strange puts on a mask after washing his hands, contaminating his clean hands by bringing them in proximity to the non-sterile environment of his face. Surgical masks must be worn before the full washing of hands. Another error is that he inserted his hands all the way through his gown to don gloves. Hands must never leave the sleeves and gloves must be put on with the sleeves still covering.
Factual error: A theater marquee is visible promoting the showing of a film called Tribeca Follies. The acronym "Tribeca" - an amalgamation of "Triangle Below Canal [Street]" - didn't come into usage until the 1970s.
Factual error: The license plate of the car that takes the protagonist to the sanitarium is GR 36E46. That's not a valid Swiss plate: GR indicates the canton of Graubünden, but other than that it is supposed to have only digits and no letters.
Factual error: As the X-Men land in Cairo, scenes reveal the destruction Magneto is wreaking around the world, where it is simultaneously daylight in New York, Sydney and Cairo - it is possible for it to be daylight in two of these locations at once, but not all three. (01:46:00)
Factual error: At the start Bruce Wayne runs into a massive dust cloud formed from the falling building. In the scenes that follow he and the other people have very little or no dust on them at all - they should be completely covered and choking on it.
Factual error: Kevin Spacey states that his company's new tower is the "tallest building in the northern hemisphere." The tallest building in the world is in the northern hemisphere - the Burj Khalifa, which has held that title since 2008, and is about 830 meters tall. Judging by the size of the new tower compared to the other buildings in New York, this building appears to be only 600 meters tall. (00:04:30)
Factual error: When Pete is riding on the back of the school bus and jumping on top of the bus in the background a New Zealand style Give Way sign is seen and also on the left hand side of the road. The film is set in the USA so this should have been on the right hand side of the road. (00:34:00)