Corrected entry: A soldier says "Nazi bastards!" The Nazi regime didn't exist in 1917, therefore this makes zero sense. (00:30:28)
Corrected entry: The soldier fires twelve rounds (two at the pilot and ten at the sniper) without ever reloading the magazine. A Lee and Enfield 303 has only 10 rounds per clip. Also the bayonet has miraculously disappeared from the end of the rifle when he crosses the broken down bridge, although we never see him take it off.
Corrected entry: The woman describes the baby as "mon fils" although it is a daughter and should be "ma fille".
Corrected entry: When Schofield leaves the truck at Écoust due to the bridge being out, he's told that the nearest intact bridge is 6 miles. However, when he is later going down-river, an intact bridge can be seen in the background.
Corrected entry: At the hospital towards the end, the doctor tells someone to go to "triage." The hospital is British. The term triage is French and comes from the Napoleonic wars and was coined by two French/Belgian doctors. The French were using the term triage during WW1 with plenty of photos to back this up. There is no evidence that the British or even the USA were using the term until about 1960 when it is mentioned by a Baltimore based medical facility. I can find no mention of its use in either WW2 or the Korean War. It only after this time that its usage becomes more widely used in the English speaking world.
Corrected entry: All the Germans in the movie are cartoon-cutout fanatics: the rescued pilot stabs to death his English teacher, the German stragglers try to kill the lone British soldier, rather than avoiding him In order to survive, as would have been more probable. By 1917, soldiers on both sides were tired of war, and not driven by some ideological fury (as Germans inculcated with Nazi ideology were in WW2). Pilots especially had a code of honour, on both sides, and treated their downed colleagues with respect. That is not to say the Germans (particularly the Prussians) weren't brutal in battle. Most were conscripts and - like their British counterparts - desperate for the war to end after three years of fierce fighting, and countless casualties.
Corrected entry: The entire premise of the movie is flawed. If the General needed to get an order to Col McKenzie, the quickest and surest means would have been to drop a message from an aircraft. In fact, the field beyond the aid station at the end of the movie would have been perfectly suitable for an aircraft of the time to land and hand-deliver a message the day before the assault.
Corrected entry: When one character floats downriver and eventually comes to a literal log-jam and swims/climbs over some corpses, there is one 'body' in particular that is obviously plastic/inflatable.
Corrected entry: When Dean-Charles Chapman (Blake) salutes Colin Firth, his sleeve slides back and you see a gold chain with a clasp. Pretty sure, but not an expert, that men didn't wear those back then. Belgian and French troops had identity bracelets, but they were not gold. British troops had standard dog tags on a leather thong around their necks.