Factual error: In various shots throughout the film "Sky TV" style satellite dishes can be seen on houses - the film is set in 1972 many years before satellite TV existed.
Factual error: The way the FBI officers, who are trailing Dooley, act is completely unprofessional. The scene where the one has to restrain the other after the sprinkler incident would never happen. (00:29:45)
Factual error: In the scene where, Clint is examining his scar, the scar is misplaced. It should run from the top of the sternum between the collar bones to the bottom of sternum, mid diaphragm.
Factual error: In the scene where Jack and Algy are eating muffins Jack is wearing a Burberry Check tie. The Burberry Check was not created until the 1920's. The scene takes place in mid-1890s.
Factual error: John supposedly goes to Chicago to talk to a mothman expert, but it shows the two of them walking into The Mellon Institute which is actually in Pittsburgh.