John Corigliano wrote a complete score to the original cut, with the National Philharmonic Orchestra in London, conducted by Leonard Slatkin. Corigliano's score was rejected when re-shoots made the movie more action-driven. Because Corigliano was not interested in scoring the new version, stating it was now the kind of film he would never have signed up for, a new score was commissioned from Howard Shore.
Ray Winstone's name "Jedburgh" may be a reference to the secret operation that parachuted British and American commandos into occupied France during WWII. All were subject to torture and execution if captured by the Germans under Adolf Hitler's infamous "Commando" order.
When Whitehouse comes to Craven's house he asks if Craven remembers a cop who was transferred and ultimately committed suicide as a result of arresting someone named "Whitey". That may refer to James 'Whitey' Bulger, a real-life Boston crime boss and killer who, as an FBI informant, was off limits to law enforcement until he became a fugitive in 1994 after being indicted under the RICO Act.
The trivia item below may give away important plot points.
This is the second film in which Danny Huston is part of a company involved in a conspiracy and is also willing to kill to keep its secrets. The first film was The Constant Gardener (2005). In both films the main character is trying to solve the murder of a loved one and ends up being killed by the company.