The forensic team and other extras in the service tunnel were all Eurotunnel staff in costume. The forensic team was advised by a Eurotunnel train driver, who happens to be a former Forensic Scientist.
During the first meeting between Stephen Dillane and Clémence Poésy, he tells her "Steady on, Joan, I'm not looking for a war" and she answers "My name is not Joan". Clémence Poésy played the part of Joan of Arc in Jeanne Captive (2011).
While working for the series, Ben Richards worked with Hans Rosenfeldt, the Swedish writer who created The Bridge (2011). Many aspects of the first episode are virtual copies of the first episode of the Scandinavian series, including: the female lead "stripping unselfconsciously to her underwear in the office", the male lead's relationship with his teenage son, and the "sleazy journalist [being] held captive in his own car with a ticking bomb", the last of which was a sequence Richards wanted to repeat in the remake. However, Richards said that as the series progressed and the drama unfolded the storylines would diverge from the original.
In France, the series premiered on Canal+ on 11 November 2013 at 8:55 pm, with two out of ten episodes airing consecutively, and concluded on 9 December 2013. The premiere attracted 1.3 million viewers, making it one of the highest rated original series debut for the channel. The first series had an average audience of 1.04 million viewers per episode.
The debut was seen by an average of 362,000 overnight viewers, considered strong ratings for the channel. With consolidated ratings taken into account, the first episode went up to 803,000 viewers on Sky Atlantic, with an extra 90,000 viewing from its catch-up channel, Sky Atlantic +1. However, the second episode dropped a third of its overnight audience, leaving it with 236,000 viewers. The finale was seen by 267,000 overnight viewers.