When Emily Blunt's character is introduced, she is doing a planche hold. Although she needed a wire for help on long takes, she is actually capable of doing that maneuver without assistance. In fact, when discussing the introduction, a cast member said, Em, show that yoga move, and she casually demonstrated it.
Rita, (Emily Blunt), for her bravery, was nicknamed by the public The Angel of Verdun. In real life, Verdun was the site in France of the bloodiest battle of World War I in 1916. It lasted almost a year and an estimated one million men on both sides died, and Mons was the site in Belgium of a battle in 1914 and spawned tales of what many consider an otherworldly miracle.
A 1914 newspaper short story about the battle, The Bowmen, written by horror-story specialist Arthur Machen, told the tale of how during the battle, soldiers on both sides saw supernatural medieval archers appearing in the sky and causing the enemy to retreat. Despite Machen’s attempts to prevent it, his story, which was entirely fictional, quickly inspired a popular and strongly believed account of the Angels of Mons. The Battle of Verdun occurred two years later and there was no association with angelic apparitions, but Rita’s nickname does seem to be inspired by the Angels of Mons story.