Factual error: Clooney refers to the rifle as an "M14". The Rüger Mini-14 is a different rifle than the M14 (used e.g. by the Marine Corps prior to the M16).
Factual error: When Talbot is first in Gwen Conliffe's shop in London, there is a vase of flowers containing Stargazer lilies. The Stargazer lily wasn't created until 1978 by Leslie Woodriff.
Factual error: After the snake swallows the dagger - it is able to curve its body beyond that which having the dagger inside would allow.
Factual error: When Toothless zooms in and catches Astrid while she's falling, he was moving so fast that he would have pulled her leg out of the socket when he grabbed it, if not totally ripping it off. (01:19:55)
Factual error: The construction of Hadrian's Wall as shown at the end of the film is not historically accurate. A wooden wall was constructed first with a deep ditch on either side. One of the ditches should be visible as the characters approach the wall but it is not. The stone wall shown being constructed was not added until later and then it was constructed in sections. It did not become a continuous stone wall until some years later. In addition, the stone wall shown is not wide enough. Hadrian's Wall is around 2 meters wide at the top and even today you can comfortably walk on top of it.
Factual error: In the scene where Natalie Portman travels from her house to Lincoln Center she is riding the 1 subway train. The model train shown is a R142, which only serves the 2,4,5 trains. The one 1 train line is actually served by the R62A.
Factual error: In the scene where Peter & Ethan are traveling across Texas on I-120 the train reads Union Pacific, but Burlington Northern Santa Fe (BNSF) is the one that runs that track.
Factual error: During the breakfast scene with the bacon a box of Cheerios is seen on the counter with the red check mark on it. This indicates that the cereal is American Heart Association approved. The check mark campaign didn't begin until 2009 even though the movie supposedly takes place 3 years prior, in 2006.
Factual error: Just after arriving at Chicago O'Hare Airport and on their way to Ishpeming, the filmmakers are shown riding in a car through a mountainous area. There are no mountains anywhere in this vicinity. (00:34:15)
Factual error: Early in the film following Lincoln's assassination, we see a newspaper stating that Lincoln's body is being transported to his final resting place of "Springfield IL". At that time the state either wouldn't have been shortened, or "Ill." would have been used. The two letter state name abbreviations were not introduced until the 1960s, at the same time as ZIP codes.
Factual error: In the scene when they are leaving the Pittsburgh Zoo, the sign indicates to turn right for Interstate 79. However Intestate 79 is about 15 miles to the west of the zoo. Also, it is suggested that Interstate 79 is the turnpike (a tolled road), when actually Interstate 76 is the turnpike and Interstate 79 is not tolled.
Factual error: Sam is driving through a tunnel and there are also other cars driving through it. However, there are two X signs displayed in the tunnel, which should indicate that the road has been closed off and that no-one should be driving through it. (00:06:00)
Factual error: The painting "Saturno devorando a su hijo" has been in the Museo del Prado (Madrid, Spain) since 1876. Plus, it can't be a sketch as the movie states, because the original painting was a mural work that was transferred to canvas after Goya's death.
Factual error: When Barry swallows the car key on the way to the airport, he holds and swallows a Ford car key, yet they are driving a Citroen Xsara. (00:08:18)
Factual error: During the scene where they deliver electroconvulsive therapy to Kristen, the physician is seen holding the patient. Considering the level of charge delivered, the physician should have received a shock along with the patient.
Factual error: When Leslie and Scott meet at the gas station, she is pumping gas, which wouldn't have happened in New Jersey. New Jersey and Oregon are the only two US states that don't allow customers to pump gas. (00:12:00 - 00:12:30)
Factual error: Metrocity appears to be located in Michigan, but the news station on the truck starts with K, which signifies that's it's in the western half of the US.
Factual error: A fire breaks out in the hospital due to one of Abby's victims being exposed to sunlight as she's turning into a vampire, destroying that vampire and a burning a nurse to death. Modern hospitals have fire sprinklers, fire extinguishers, etc. and sensors/alarms that the fire would have activated.
Factual error: When Cobb arrives at Los Angeles International Airport and is going through immigration, the officer stamps his passport with a black stamp. All passport stamps in the United States are universally the same with a blue oval and pink letters marking the date in the center. Plus the fact that US citizens don't get their passports stamped when they return to the country.
Factual error: Adam Sandler is cooking bacon on the bug zapper, laying the meat on the outside cage. That couldn't happen, since the outside of a bug zapper is not hot and has a covered protection cage to avoid shock. (The cage is what the bacon was lying on.)