Many of the soldiers in Matt Damon's WMD unit were actual Iraq War and Afghanistan War veterans, not actors. Damon said his biggest challenge was knowing he was an actor who was giving orders to actual soldiers.
Roy Miller is based on U.S. Army Chief Warrant Officer named Monty Gonzales (Richard L. "Monty" Gonzales), who had the real-life job of hunting for weapons of mass destruction after the fall of Baghdad. Gonzales was hired as a consultant on the film.
The traffic shots of the American convoy rolling under an overpass and encountering a traffic jam as panicked crowds flee Baghdad were shot in Spain, on a brand new highway which was not yet open to the public.
The scenes of downtown Baghdad were shot in Morocco.
Paul Greengrass: [Sliney] Ben Sliney, who played himself in Greengrass' previous film United 93 (2006) makes a cameo appearance as himself again here.