Factual error: Frank, Archie and Snowy are all rural boys from New South Wales, but they all play Australian Rules football expertly. In 1915 Australian Rules was almost unknown outside of Melbourne. In a time before television or film they wouldn't even know what the ball looked like. In fact the game was only established in Sydney in the 1980s, and is still not terribly popular there. There is no way that three people from New South Wales would know how to play the game in 1915, let alone with such skill.
Factual error: Mel Gibson sits around the campfire at the railway camp with the lads, reading newspaper reports of the April 25, 1915 landing at Gallipoli. The 3rd Light Horse Brigade (including the 10th Light Horse Regiment from Western Australia) landed at Gallipoli on 20 May 1915. This would have given him less than 3 weeks to enlist, train, travel to Egypt by ship and land on the Peninsula. A bit of a stretch. In reality, the 10 Light Horse regiment was raised in October 1914, with the 1st-3rd reinforcements departing Fremantle February 19-22, 1915.
Factual error: Mel Gibson and Mark Lee leave their jobs working on the Pichi Richi Railway (north of Adelaide) to join the Australian Light Horse Brigade (about to sail to Turkey from Perth in 1914). To do this, we see them travel over 1000 miles across the Nullarbor Plain by train. But the tracks were not laid until 1927.
Other mistake: In the scene where Mel Gibson is playing AFL with his fellow soldiers during training in Cairo, we see him wearing a digital wrist watch when he whistles and raises his arm. (00:49:30)
Factual error: Before the heroes are about to go over the top of the trenches to certain death, the Captain plays a recording on his gramophone of Pachabel's canon, a now famous piece of music, full of pathos and very suitable to the scene. However, although written in 17th century Venice, the music lay forgotten in a dusty library until the 1960s.
Other mistake: During the scene of the ill-fated charge by the Australians, some of the bayonets on Turkish soldiers' rifles wobble. Apparently, the fake bayonets were made of rubber.
Factual error: The two heroes are seen arriving at Adelaide Station (name changed to Perth) behind a South Australian RX Class steam locomotive running on 5 feet 3 inch gauge rails. The Western Australian Railway system serving Perth Station at the time used 3 feet 6 inch gauge rails and more recently standard gauge, but never the Irish gauge. The locomotive is much too big for authenticity.