The producers arranged for every member of Eurotunnel staff to receive a copy of the series on DVD as a thank you for their assistance in the making of the series. As well as some being extras, Eurotunnel staff gave up their time to advise the production team as well as more mundane tasks such as escorting the production teams and actors around what are secure sites.

When filming on board trains and in the tunnel, the extras are all actual Eurotunnel staff members. Those who took part were invited to a VIP premiere at a local cinema before the series aired.

This series is the final television appearance of Liz Smith who appears in Series 1, Episodes 2 and 3 at the age of 91 despite having previously suffered a stroke. She died three years later, aged 95.

Although none of the characters in The Tunnel share their names with equivalent characters in The Bridge, many names are similar. Martin Rohde becomes Karl Roebuck, his son August becomes Adam. Daniel Ferbe becomes Danny Hillier, Stefan Lindberg becomes Stephen Beaumont (Mont and Berg are French and Swedish words for mountain) and Charlotte Söringer becomes Charlotte Joubert.

Liz Smith's last acting role before she retired.