Revealing mistake: During the flat fire, the girl tosses her baby to ADO Coleman. Just before he catches it, you can see that the falling baby is a doll.
Episode #4.7 - S4-E7
Factual error: In this episode Blackwall Station is shown as a London Underground tube station. Blackwall Station is a Docklands Light Rail (DLR) station. Also look at the destination sign on the front of the train, which reads 'THAMES LINE', No such line/station exists on the London Underground.