The film's title, "Cleanskin," can have two different meanings. It can either refer to an undercover operative unknown to his intended targets, or it can refer to an extremist who is unknown to the security services, as he or she has had no previous convictions.
One news article has a scrolling text declaring that Spurs have won the Champions League. As of 2018, this still hasn't happened.
Over 150 extras were used in the bombing scene set in London's Borough Market.