Factual error: While handling the ignition coil cable to the distributor cap, Joe Pesci tells De Niro that the timing chain needs adjustment in his truck. A truck of that year with an inline Chevy motor would not have a timing chain at all, instead this truck would be equipped with a direct drive timing gear. Even if it had a timing chain, it would be behind the water pump and a cover. It would have been a several hour job to replace, not possible to adjust it.
Factual error: During Lee Iacocca's slide presentation to Henry Ford II in 1963, there are two slides that reference James Bond. One shows him standing next to the Aston Martin DB5, which made its debut in "Goldfinger" in 1964, and another shows a still image from "Thunderball", which was released in 1965.
Factual error: Tommy is wearing a Hulkamania shirt while the band is being assembled together. The band was formed in 1981. Hulkamania didn't start until 1984.
Factual error: As well as the sergeant's stripes on his cuff, Sergeant O'Neil wears three pips on his epaulettes, which would indicate a much more senior rank and would not be worn together with the stripes.
Factual error: Eve Curie is shown as having been born before the Curies are nominated for the Nobel Prize in physics, which they eventually won in 1903. However, Even Curie wasn't born until December 6th, 1904.
Factual error: The scenes set at Wrestlemania XXX (2014) were filmed at a RAW show in 2018 - fans are visible in the background wearing wrestling merchandise more recent than 2014.
Factual error: Pope Benedict and Cardinal Jorge Bergoglio are hanging out in the room by the Sistine Chapel having a pizza and a drink together. The drink of choice is Fanta, apparently Joseph Ratzinger's favourite beverage. The scene is supposed to happen in 2012, but the label of the bottle is a more modern one, introduced in 2016. (01:34:20)
Factual error: When we see Elton John's father Stanley in RAF uniform at the beginning of the film he is wearing other ranks' uniform. Stanley was commissioned in 1944, three years before Elton was born, and served as a commissioned officer until his retirement as a squadron leader in 1963. He should be wearing officer's uniform.
Factual error: Three details were omitted on the Miller's car's license plate: the month was missing in the upper left-hand corner; a "15" (2015) sticker was missing in the center of the plate; and, "Show Me State" was not written at the top below "Missouri." (00:16:46)
Factual error: There is a modern digital electric meter in the record store - not what it would look like in the era of the movie.
Factual error: In 1915 Tolkien was commissioned as a Second Lieutenant with the Lancashire Fusiliers. He (plus various other officers) is constantly shown in the film wearing bright metal cap badge, collar badges and shoulder titles on his Service Dress tunic and greatcoat. However, in the Lancashire Fusiliers officers did not wear shoulder titles on their SD tunics/greatcoats, and their cap/collar badges would have been in a darkened bronze finish, not bright metal (which was for Other Ranks and NCO's).