Canadian identity post-Confederation, when it became a self-governing dominion within the British Empire, was heavily attached to celebrating its British imperial connections and culture in the late 19th and early 20th century. This was truer in English Canada than in French Canada, which often pushed back against this anglo-centric version of English-Canadian nationalism.

The British Army had a presence in Canada since the fall of New France, they fought to defend Canada during the American Revolution and the War of 1812, and until Canada developed its own army had been responsible for its defence. The Canadian army with its regimental system was largely modeled on the British one and adopted many of its traditions. Canada's entry into WWI in 1914 was definitely motivated by duty to king and country, at least in English Canada. But the great cost in lives during the war and Canada's feats of arms at Vimy Ridge (succeeding where its allies had failed), it has been argued, was a crucible of fire that further instilled a sense of Canadian identity that became more independent of Britain, which had often been dismissive and paternalistic in its treatment of Dominion forces in the war. There was also the conscription crisis in 1917, which pitted English Canada against French Canadians who didn't want to fight in what they perceived was a British imperial war. Canada made a point of signing the Treaty of Versailles independently of Britain.

Canada entered WWII motivated largely by English Canada's lingering duty to king and country, but it declared war on Germany separately from Britain. Canada was not ready, like other nations, for war in 1939 so they were ill-prepared when Britain asked for help to defend Hong Kong in 1941. Canada's first land battle in WWII was not in Europe -- but in Asia against a hardened Japanese Army, and it would pay dearly there for fulfilling its imperial duty. By Normandy in 1944, the Canadian army was experienced, with its own battle scars in Dieppe and Italy. It would prevail in dislodging the Germans from the Netherlands, where its allies had struggled in Operation Market Garden. While there was still a tendency to group Canada with British imperial forces, many of Canada's important victories in Italy, Normandy and Holland were their own, under Canadian commanders.

So while there is some truth that British culture and traditions were still important to English Canadian identity then, these were less so for French Canadians on the front, outside of regimental pride in the 'band of brothers' sense. The moviemakers likely didn't quite know how to portray "Canadian" identity outside of its anglo, British connections.