Goofs

When Teddy delivers Damien's letter to Sinead, he puts his cap on, gets on his motorcycle, and puts his goggles on the handlebar. In a wide shot, the goggles are around his neck.

After being executed at the end of the movie no bullet holes are visible on any part of Damien's body. There is also no blood.

The British troops wear medal ribbons from the Great War (1914-18). The film is set in 1919-21 but ribbons were not issued until 1922 by which time British troops had gone.

The foot patrol of the Free State is inaccurate and is based instead on the British Army's foot patrols.

At one point, the characters sing Amhrán na bhFiann, the Irish language version of The Soldier's Song, which would go on to become Ireland's national anthem. Whilst The Soldier's Song was known at the time, the version in Irish was not written until 1923, three years after the film is set.

When the players are arguing with the referee during the hurling game, a modern car is parked in the distance, to the left of the referee's head.

As Damien talks to the driver at the train station, modern concrete markings for the visually impaired are visible along the platform edge.

As the Black and Tans drive through the village, they pass a blue house with modern PVC windows.

A few of the IRA members are seen armed with German Mauser Kar98k rifles. However, these rifles weren't introduced until 1935, whereas the film takes place in 1920-1922.

Two machine guns appear in the film, a Vickers and a Lewis. The sounds they make when firing are reversed; the Vickers sounds like a Lewis and vice versa.

The priest says "in nomine patris... et spiritus sanctus". The correct genitive is "sancti". A priest would not make this error.