Originally this film was much longer and larger in scope running approximately two and half hours and this is the cut that Director Peter Berg wanted to release, which featured more character development and more dramatic overtones to the story. Universal balked at the idea and forced Berg to cut down the film to its current length much to his dismay.
The end of the movie dedicates it to Thomas Aguilar, Lance Gunnin and Nick Papac, all crew members who died during production. Thomas Aguilar (Tom Aguilar, prop maker) died one week after being admitted to the hospital for stomach pain and subsequently discovering he had prostate cancer. Lance Gunnin (construction worker) was killed in a motorcycle accident on his way to the set and Nick Papac (prop master) died in an on-set collision between his Gator all-terrain vehicle and an SUV.
The production team had originally wanted to shoot the film on location in Saudi Arabia, but political and logistical issues made this far too difficult. Instead, Tom Duffield and the production design team re-constructed exterior urban scenes for the chase and shootout on an empty lot near Mesa, Arizona, using photographs from the internet and some that director Peter Berg had taken on a visit to the country prior to filming. Some additional on location photography was shot in Abu Dhabi, United Arab Emirates. This includes the Prince's palace and larger exteriors with skyscrapers, major city streets and highways.
When Director Peter Berg was trying to get Marcus Luttrell to assist with the making of the movie Lone Survivor, Berg told Luttrell to watch his movie The Kingdom, and if he didn't like it, Berg said he would not bother Luttrell again.
Reportedly, one of the extras, Austin Martin, was commended by several of the main cast, including Jamie Foxx, for his very realistic looking beard. The actors believed it to be skillful work by the costume department, when, in reality, it was entirely natural.
When Mayes makes a comment about the group of FBI agents being in the jungle, Leavitt calls her Axl, referring to Axl Rose the singer of the band Guns N' Roses who had a hit with "Welcome To The Jungle". "Welcome To The Jungle" is also the German title for The Rundown (2003), a previous movie by director Peter Berg.
A number of extras used in the scenes at the U.S. Contractor compound were not actually Arabic. They were Hispanic local area residents. Makeup was applied to their faces to give them more of a middle-eastern appearance.
The trivia item below may give away important plot points.
An earlier draft of the script had Sgt. Haytham being extremely disaffected after being tortured by his own government for his suspected involvement in the bombing. The earlier ending had Al-Ghazi surviving, but instead Haytham says goodbye to the FBI team at the air base with a hidden bomb strapped to his chest. Sykes tackles Haytham away from the group, but Haytham detonates it before Sykes can get clear.