Factual error: About 20 minutes in, the group find a Welsh miners' group in the phone book. The character who is making the call speaks the first two digits of the phone number: "0, 1,..." The movie is set in 1984, when the dialling code for that district was "0639" In that year, "01" was the code for London, not Wales.
Factual error: As the marchers start through the streets before they gather at the Edmund Pettis Bridge, they pass by a shop with a Pepsi sign. The Pepsi logo, however, is from the 1980s-1990s.
Factual error: Roland enters the train to go to the war, in 1914, with "Spanish Flu", but that was the (wrong) name given to the 1918 flu pandemic, which lasted from spring 1918 through spring or early summer 1919.