The CIA analyst refers to King's Cross tube station as King's Crossing.
An MI6 agent is depicted operating inside the UK. MI6 (actually known as Secret Intelligence Service) only operate outside the UK, MI5 (Security Service) operate inside the UK. Additionally an SIS agent would not identify himself as MI6 to a UK policeman, he would either say SIS if he were telling the truth or perhaps more likely as a Security Service agent.
The same MI6 agent refers to a mobile/cellphone as a "celly". In the UK "mobile phone" is the normal term - "cellphone" is an Americanism.