When Harry is back home in Manchester he seems to have his Sam Browne belt on backwards, with the buckle on his back rather than at the front.
Harry places Kasia's wedding back on her ring finger, left hand saying it will make her less suspicious, but in Poland, a wedding ring would traditionally be worn on her right hand, so wearing it on her left have would actually make the Germans very suspicious of her.
When Henriette is escorted to the truck that will take her to Ravensbruck, her escorts walk in front of her. But a prisoner would never be led. Her escorts would have walked behind her, which would place her, by design, at a disadvantage Otherwise, any action she might choose to take (other than going to where they want her to go) would come as a surprise to them, and that is the last thing any guard wants.