影片對白 I'm a sergeant of Massachusetts State Police, who the fuck are you? I erased you!
思想火花 兩部片子的敘述核心本就不同。從片名上，港版的叫《無間道》、《Infernal Affairs》（《地獄之事》），美版的叫《The Departed》（《背叛者》），前者帶有佛教的反思意味，充滿了個人內心的情感糾纏，探討了自我迷失和認知這些更深層的問題。而后者更注重抓內鬼這一情節的復雜性，用暴力和粗口將影片涂上重重的黑色。
考考你 乘熱打鐵
5. Can't wait
"等不及（要做某事）"的意思，例如：I can't wait to see Papa.
6. Suffolk County
Boston 位于Suffolk County，是那里的首府。
7. Squeeze off
意思是"Fire a gun"，例如：He squeezed off one shot after another but didn't bring down a single crow.
8. Go on record
意思是"Embrace a position publicly 公開表明立場"，例如： I want to go on record in favor of the mayor's reelection.
這個片語也寫作"for the record"，例如： For the record, we support sending troops there.
文化面面觀
Federal Bureau Of Investigation美國聯邦調查局
The United States Federal Bureau of Investigation (FBI) is the nation's primary federal investigative service. As the investigative arm of the Department of Justice, FBI was created in 1908 by Attorney General Charles J. Bonaparte over the initial opposition of Congress who feared political abuse of such powers.
The mission of the FBI is to uphold and enforce federal criminal laws, aid international, state, and local police and investigative services when appropriate, and to protect the United States against terrorism and threats to national interests.
The FBI employs nearly 30,000 men and women, including 12,000 special agents. The organization, headquartered in Washington, D.C., is field-oriented, maintaining a network of 56 domestic field offices, 45 foreign posts, and 400 satellite offices (resident agencies). The agency relies on both foreign and domestic intelligence information, to aid its anti-terror operations. As a law enforcement authority, the FBI only has jurisdiction in interstate, or federal, crimes.
During and after World War I, the FBI investigated draft resisters, violators of the Espionage Act of 1917, and alien residents suspected of radicalism. This kind of surveillance marked a shift away from criminal investigations toward individuals thought to be domestic security threats, a group including such diverse figures as Jane Addams and Fiorello La Guardia. Such misuse of the FBI's powers led to reorganization in 1924. The bureau received orders not to engage in wiretapping or to investigate the political activities of individuals. J. Edgar Hoover, appointed director, professionalized the bureau, placing appointments and promotions on a merit basis and developing new crime-fighting techniques.
Despite the ban on political surveillance, World War II and the cold war prompted a wide expansion of security investigations. Under the guise of national security the FBI amassed over thirty-five thousand linear feet of files on individual citizens. Following the death of Hoover and the Watergate scandal in which it was involved, Congress and the attorney general again issued guidelines designed to prevent such abuse. In the late 1970s the FBI shifted its investigations toward organized and white-collar crime.
