Episode 1, The NY City Subway Plot, at 4:05 the narrator brings up the July 7, 2005 London Underground terror attack. The footage of the bombs exploding on commuters is actually the Madrid 2004 train bombing! The London 2005 explosions were NOT caught on camera!
This series received so many complaints for its production choices that it even developed its own Reddit page. Complaints ran from the simply lazy use of reversed US street scenes to sit in for events in the UK, to the despicable idea of using the footage of the Madrid subway bombing as if it were the UK subway attack complete with canned screams of agony since the original security footage had no audio track at all.
Episode 3, Cargo bomb plot, the footage of the blown plane is taken from the movie U S Marshals.