Women drawing lines on the back of their legs was a common practice in WW2 Britain. As materials like silk were reserved for military use, some women would "wear" fake stockings by painting their legs brown (with makeup and, sometimes, even gravy) and then drawing lines to simulate the seams.
The flooding of the Balham tube station during the Blitz was also a key plot point in the 2007 film, Atonement. A young Saorise Ronan also appeared in Atonement. In this film the tube station depicted was London Bridge
Gerald serves George bacon and eggs and a glass of milk for breakfast, along with a piece of cheese. These items were heavily rationed in Britain during WW2, the quantity amounting to two-weeks' rations in some cases. This gives audiences an idea of how much Gerald cares for his grandson.
Stepney Green is incorrectly shown as a 'tube' station. Unlike Bethnal Green, Stepney Green is a sub-surface station, built using a 'cut and cover' method and so does not have tunnelled stairs leading down to it. It has flat walls, unlike the curved tube walls shown in the film, which are typical of tube stations,