My Dad was in France in 1940. He made it out at Brest as part of Operation Ariel. It took a month to get from Reims to Brest - I have the diary he kept at the time, discovered after his death. He spoke about his experiences very rarely.
The one thing I immediately noticed in the trailer is how relatively clean everybody and everything looks. In Dad's diary one of the big events he related was having a wash in a river - once - in a month.