A recurrent song throughout this series is "I Love To Love (But My Baby Loves To Dance)," by British disco artist Tina Charles (circa 1976).
Greater London Police is fictional and is likely used to avoid licensing disagreements with the real life Metropolitan Police Service.
Stellan Skarsgård saying of his role as DI River --- "There's not much research you can do because his condition doesn't really exist as we know it. It's a combination of problems, because he's not like people who hear voices -they're usually schizophrenic and lack empathy and he does not. But it doesn't make it less truthful. What attracted me to the script is that it didn't look like any other script I've ever read."
Talking about recording the scenes involving manifests, Stellan Skarsgård said: "How we practically do it is we usually shoot the scene first with the actor who plays the manifest and then we shoot the same scene exactly the same way but without anybody there. It looks fantastic, because you walk around, you gesture and talk to somebody that isn't there and it's quite interesting visually. To me, I'm the kind of actor who doesn't want to act towards a mark beside the camera; I want the real actor to be there, and I feed so much off the other actors. So it's very unnatural to me to do it, but since we always do the scene with the actor first I have a very clear memory and then we do it with the real actor saying the lines, so I still get a response and it becomes more like playing a game of ping pong."
Filming took place across at least eight London Boroughs - Lambeth, Islington, Camden, Hackney, Southwark, Redbridge, Newham, Tower Hamlets and Lewisham. Notable roads, buildings and landmarks include Clerkenwell Road in Islington, Southwark Park, Globe Theatre and Millennium Bridge in Southwark, and Stratford International in Newham.