The title comes from a line of dialog written in the script. The line "terminate with extreme prejudice" first appears on film in Apocalypse Now (although it originates in the Bernard Conners novel "Don't Embarrass the Bureau"). Both films were written by John Milius.
The opening of the film which includes the military backgrounds of each member of Michael Ironside's mercenaries, was inspired by the similar opening to the hit TV show, The A-Team.