Factual error: Midway through the film, the IRA flying column successfully ambushes a motorised British patrol. Immediately afterwards, when the column's survivors are milling about on the roadway, one IRA man is shown to be armed with a German Mauser Kar 98k bolt action rifle. This is historically incorrect, as this weapon did not go into production until after Hitler's assumption of power in the 1930's - at least thirteen years after the events depicted in the film.
Factual error: When the volunteers are in the mountains, mature conifer plantations can be seen in the background. There are even some areas where the crop has been harvested. Mountain areas in Cork were not planted with conifers until the 1960's, at the earliest. Felling of the crop takes place at least 30 years later, showing that the filming took place more than 60 years after the War of Independence.