In the scene when they torture Troy Barlow with electric shocks, they shocked Mark Wahlberg for real. He said he wanted to get into the role, and since they had all the equipment there, they hooked him up and gave him a shock.
Sayed Moustafa Al-Qazwini, who plays an Iraqi defector who sells Maj. Gates cars stolen from Kuwait, was in real life tortured and kicked in the eye by Saddam Hussein's security forces, blinding him in that eye. Like many advisors and extras in the film, he is an actual refugee from Iraq.
In the original posters for the film, David O. Russell gets full writing credit, although the story is based on a draft written by John Ridley. It wasn't until Ridley took legal action that he received a "Story by" credit. Ridley blocked a novelization of the screenplay from being published. According to Ridley, he wrote the script as an experiment to see how fast he could write and sell a script. It took him seven days to write it, and Warner Brothers bought it 18 days later.
In the celebratory scene in the tent back at base camp, several soldiers are seen to be drinking what appears to be mouthwash. During the Gulf War, Saudi Arabia's Islamic-based ban on alcohol forced many soldiers to become more ingenious in obtaining their favorite vices. In this case, they asked loved ones to send them vodka with added blue food coloring in mouthwash bottles.
In the scene where the three soldiers enter the secret room in the bunker with the stolen stuff and TV sets in it, you can see Capt. Said (Saïd Taghmaoui) watch the opening credits of the French movie La Haine (1995) on a screen. That was the first real movie he had a role in, also under his real name Said.
The role of Archie Gates was originally written for Clint Eastwood but Russell decided he wanted a younger actor. Clooney aggressively pursued the role but Russell wanted Nicolas Cage instead. But when Cage was cast in Bringing Out the Dead (1999), Russell settled for Clooney.
Clooney, a notorious prankster, played a prank on Nora Dunn by putting an apple on the antenna of a Humvee and catapulting it, hitting her on the forehead. The only cast member Clooney did not prank was Ice Cube saying, "Cube's not gonna take it. He doesn't have to. He's from South Central."
Barlow, Vig, and Elgin are wearing the patch of the U.S. Civil Affairs/Psychological Operations Command, and indeed, Barlow identifies himself as being a Civil Affairs Soldier. Barlow also makes reference to being a reservist, which rings true given that two of the three Army Civil Affairs groups are Reserve Component.
Archie Gates' uniform indicates that he is a Special Forces-qualified, Ranger-qualified member of the Combat Applications Group (CAG), formerly known as the Special Forces Operational Detachment "D", but more commonly known as "Delta Force." He is referred to as having been "with Delta." He also wears on his uniform the Combat Infantryman Badge, the Master Parachutist badge, the Pathfinder badge, and the SCUBA Diver qualification badge.
The procedure used to re-inflate Troy Barlow's collapsed lung is called a "needle chest decompression", and is taught in the U.S. Army Combat Lifesaver course. Although the entire procedure is not shown, the parts that do appear in the film appear to have been performed correctly.
The role of Major Archie Gates was offered to Nick Nolte, who turned it down, saying he was too old. Jeff Bridges wanted to play Gates, but was turned down as a result of the poor box office run of The Big Lebowski (1998).
David O. Russell never wanted George Clooney for the lead role, accepting him only after his first choices Clint Eastwood, Mel Gibson, Nicolas Cage, and Dustin Hoffman all turned down the part. As a result, his relationship with Clooney was tense during filming, culminating in a fist fight after Clooney objected to the way O'Russell was treating an extra. After the premiere, Clooney said, while he respected O'Russell's talent, would never work with the director again.
At the beginning of the film there's a disclaimer explaining that the strange look of the film was intended by director David O. Russell. The vibrant color is due to the fact that they used "Ektachrome" slide transparency film instead of standard film stock, and the "bleach bypass" process actually gave the prints a much deeper black. The silver halide is completely opaque, thus a "true" black. Leaving all of that silver on the prints resulted in a much higher cost for distribution however.