Factual error: Take a look at Google Earth - the section of the Golden Gate Bridge Magneto breaks off (about a mile - tower to tower plus a section each end) isn't anywhere near long enough to reach Alcatraz from anywhere on the mainland.
Factual error: In the car at the beginning of the movie, Jean uses her telekinetic powers to switch the radio from a station playing "By the time I get to Phoenix" by Glen Campbell to Warren Zevon's "Werewolves of London." It's 1975, and Zevon recorded the song only in 1978 (although the song itself had already been written in 1975, other artists played it in live concerts in the Fall of that year). (00:01:30)
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 helicopter markings and paint schemes are exclusive ONLY to POTUS (President of the United States). Senator Kelly, even thought he's trying to get a Presidential bid, wouldn't be allowed to fly around in aircraft marked like that. (00:30:10)
Factual error: After the Oklahoma City casino incident, it shows a brief scene where Pierce picks up Dr. Rice. The sign in the background says "Ada 15, Oklahoma City 90" on Highway 81. That highway in Oklahoma is, in fact, a real road but it is no where near Ada. The closest area that is 90 miles from OKC would be around Duncan, which is well over 50 miles from Ada. (01:06:20)
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: When Wolverine is being chased after the explosion of the barn, there's a Humvee chasing the motorcycle. The movie is supposed to take place in the late 70's - the Humvee started production in 1984 and started service in the late 80's.
Factual error: When Magneto enters RFK stadium, a groundskeeper is lining a baseball field. RFK stadium did not host baseball in 1973, as the Washington Senators had moved to Texas to become the Texas Rangers after the 1971 season. In 1973, the only team playing in RFK regularly was the Washington Redskins of the NFL. In addition, the Paris Peace Accords were signed in January of 1973; so there wouldn't be green grass inside the stadium, regardless of what sports were being played there.
Factual error: In the Shinkansen fighting scene, the railway line is seen having color light signals along its way. But the Shinkansen uses a signalling system that doesn't involve the use of light signals at all.
Factual error: When Deadpool is starved of oxygen, then causes an explosion, it is implied that the excess of oxygen, coupled with a heat source (match), causes the chain reaction which blows up the oxygen tanks. However, for a chain reaction to occur, fuel is also needed. Combustion is an oxidation of fuel. The only fuel present which is hot enough is the match. The hoses/ pipes and the tanks would not be flammable.
Factual error: In the scene where Wolverine is shot in the head the bullet stays in place until it falls off. Wolverine's skull is indestructible Adamantium (that doesn't even bend slightly from the impact), and an object that applies a certain amount of energy towards another object has the same energy applied to it in return. Considering the bullet's high speed (which means high energy) and the fact that there is not enough material around Wolverine's skull to absorb the bullet's energy, the bullet should have bounced right out.
Factual error: The 7 barrels Wade is on are only 55 gallon drums, totalling 385 gallons, not the 1200 he states. He is also on kerosene, which is not high octane fuel and burns way more slowly than shown. (00:01:53 - 00:02:37)