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.
Revealing mistake: In the episode when ACO Bulstrode is looking at the newspaper cut-out of the appliance crash (the one that Bayleaf was involved in), look closely at the cut-out. The whole article consists of the same paragraph written twice. Seemed the producers were too lazy to write a full article, hoping no-one would notice.