Monopoly games really were used in WWII to help people escape. Allied intelligence sent packages to their POWs that featured clandestine escape kits, which included tools like compasses, metal files, money, and, most importantly, maps all disguised as parts of the game.
After shooting, lead actress Sarah Megan Thomas's left Achilles tendon ruptured. The rupture occurred due to complications of playing Virginia Hall on screen (a historical character with a wooden left leg). Thomas needed surgery and extensive rehab to repair the tendon.
This basic story was originally told in a 1950's black and white version called "Odette".
Stana Katic reprises her insanely posh (and grammatically faultless) British accent, previously heard in Castle "The Final Frontier" - where she voiced the ship computer. The character of Vera Atkins is supposed to be of direct Jewish decent, so one assumes the character used the accent to hide this fact and to fit in with her surroundings.