Paul Gross wrote and directed this film, and its closing song "After the War." His grandfather, Michael Joseph Dunne, a WWI vet, once confessed to a young Gross about bayoneting a young lad in the forehead. Gross later said on Dunne's deathbed he was muttering for forgiveness and he was the only one who knew what was being talked about.
When filming the Battle of Passchendaele, Paul Gross was very meticulous about maintaining historical accuracy. He would keep various photos of the real battlefield and compare them with how the set looked.
At the time of release, the most expensive Canadian film ever produced costing $20 million in 2008 Canadian dollars.
Part of the funding came from the government of Alberta, which is also where it was filmed.
Extras were not provided with 5mm wet suits to make the hours and days of sitting and running in wet, muddy costumes bearable. Many extras left after one day. A German full-length jacket could weigh up to 60 lbs (27 kg.) when wet and caked with mud. Uniforms were not laundered once during filming to give the image of authenticity.