Edward Norton was briefly considered for the role of Guy, but upon reading the script he lobbied for the role of King Baldwin. Because the King appears behind a mask, he requested not to be credited. However, his name was put back in the video releases of the film.

Director Ridley Scott and Writer William Monahan felt that the unnamed character played by David Thewlis was an embodiment of God, or at the very least, an angel on a mission from God. This is not at all apparent in the theatrical cut, but in the Director's Cut, there are two scenes which strongly hint at it--one where the character seemingly disappears after a conversation with Balian (Orlando Bloom), the other where he seems to "resurrect" Balian after he is attacked and injured by three assassins.

Ridley Scott received many letters of thanks and congratulations from Muslim groups for his even-handed depiction of the religion.

After being cast in the role of Godfrey, Liam Neeson realized he knew nothing about the Crusades and began his research with "The Complete Idiots Guide to the Crusades" by Paul L. Williams, a book Neeson calls "extremely informative".

After the film was pitched to them, studio marketing executives took it to be an action-adventure hybrid, rather than what Ridley Scott and William Monahan intended it to be--a historical epic examining religious conflict. 20th Century Fox promoted the film as an action movie with heavy elements of romance, and in the advertising campaign it made much of the "From the Director of Gladiator (2000) slogan. When Scott presented the 194-minute version of the film to the studio, it balked at the length, and studio head Tom Rothman ordered the film to be trimmed down to two hours, feeling people wouldn't go to see a three-hour movie. Ultimately, Rothman's decision backfired, as the film gained mixed reviews (with many commenting that the film seemed "incomplete"), and it did not perform well at the U.S. box-office.

Ridley Scott disowned the theatrical cut. He claims that the Director's Cut is the definitive version.

King Mohamed VI of Morocco is a friend of Ridley Scott, and personally provided the production with a detachment of 1,500 military personnel and equipment; often these personnel depicted both Christian and Muslim armies, with simply a change of costume, and a shift in location between scenes.

Ridley Scott offered the small role of English King Richard I to Russell Crowe, but due to scheduling conflicts, Crowe was unable to do it. The part eventually went to Iain Glen.

There were roughly twelve to fifteen thousand costumes made for the film, and each one had thirteen to fifteen separate components (helmets, boots, gloves, several pieces of chainmail, belts, scabbards, etc.).

Orlando Bloom had just completed filming Troy (2004) when he received the screenplay for Kingdom of Heaven (2005) and was initially reluctant to even read the script for another historical epic. Knowing it was being put together by Ridley Scott, convinced him to give it a chance.

To create both the theatrical cut, and the Director's Cut, Editor Dody Dorn worked for fifteen months straight. The average film takes, at most, four or five months to edit.

After the team arrived in Morocco, an article appeared in the "Daily Telegraph" on January 20, 2004, claiming that the film "panders to Osama bin Laden". However, the writer of the article was quickly exposed as not having seen the screenplay. Subsequently, however, a copy of the screenplay was leaked to the world press, and provoked a strong reaction in terms of its depiction of Muslims. In an article on August 12, 2004, Professor Khaled Abu el-Fadl wrote, "I believe this movie teaches people to hate Muslims. There is a stereotype of the Muslim as constantly stupid, retarded, backward, unable to think in complex forms." This new sway in criticism greatly concerned King Mohamed VI, who came to fear for Ridley Scott's safety, and as such, Mohammad provided Scott with four bodyguards.

Three 60-foot siege towers were built for the film, using the technology of the period. Each one weighed 25 tons. To accomplish the scene where a number of siege towers collapse, one of the real towers was knocked over on set and filmed from 11 different positions and locations. Various shots of the single tower falling were then composited together to give the impression that several towers had collapsed in different ways and in different directions.

The French village at the start and end of the film was built near Huesca, a small city in northern Spain. The castle seen in these scenes is a real crusader castle built in 1076, Castillo de Loarre. As he would do in Morocco when building Ibelin, Production Designer Arthur Max decided to use traditional building techniques and local craftsmen. In Galicia he found craftsmen who still did slate roofs, thatching, and stone dry-walling, and these men were employed to build the village set.

The flag budget for the film was 250,000 dollars. In total, 1,200 flags, comprising 650 separate designs, were made in Spain, England, Morocco, and India.

After being cast as the Hospitaler, David Thewlis visited the Hospitalers' Museum at St. John's Gate in London, near where he lives. While there, he discovered that his flat was actually built on the remains of the old priory of the Hospitalers' headquarters.

Most exterior filming took place in Ouarzazate, Morocco, where Ridley Scott had also filmed Gladiator (2000) and Black Hawk Down (2001). A massive replica of Jerusalem was constructed in the desert. The set contained 28,000 square meters (301,389 square feet) of wall, and used 6,000 tons of plaster. The front of the set was 1,200 feet (365.76 meters) long, and the walls were 56 feet (17 meters) tall.

The filming of the siege of Jerusalem took twenty-one days. In real-life, the siege itself lasted only thirteen days.

Hamid Dabashi, Professor of Iranian studies at Columbia University, was the film's main historical consultant.

The screenplay originally began with Balian (Orlando Bloom) awakening after the shipwreck. Screenwriter William Monahan had wanted to begin the story with the death of Balian's wife in France, but had feared that that would make the screenplay too long. When Ridley Scott became interested in the project, he told Monahan not to worry about length, and to begin the screenplay where he wanted to begin it.

The shipwreck sequence was the last scene to be added before the film's release. Since it is too expensive to build one ship from scratch, only to destroy it, Ridley Scott opted to use a combination of outtakes of the siege of Jerusalem, shots of Balian with his attire digitally altered, a CGI model of a ship, archive footage of a heavy sea storm, and outtakes from his own earlier film White Squall (1996). The creation of this "non-existent scene" is explained in detail on the four-disc Director's Cut DVD.

Orlando Bloom gained twenty pounds of muscle for this movie.

In the "burning bush" scene in the Director's Cut of the film, Balian's horse jumps as the camera pans across the desert, just after the character of the Hospitaler (David Thewlis) has "disappeared", thus enhancing the sense that the character is a spirit of sorts. According to Ridley Scott, the horse did this completely spontaneously as the scene was being shot.

Michael Sheen (who plays the priest) auditioned for the role of Baldwin IV (ultimately played by Edward Norton).

Edward Norton filmed his part in two weeks.

The reason Jeremy Irons' character was renamed Tiberias (as opposed to his 'real' name, Raymond III of Tripoli) was because the studio felt audiences would get confused with two major characters both having names beginning with R (the other being Raynald de Chatillon (Brendan Gleeson), and so they ordered writer William Monahan to change the name of one of them.

Most of the swords and battle-axes were made from lightweight aluminum.

During the last day of the siege if you look closely you can see a burning siege tower, during production one of the towers caught fire and was subsequently burned down (one of the charges for the firebombs hadn't been put out properly and was left smoldering overnight; it eventually caught the tower and lit it up). Both director/producer Ridley Scott and production designer Arthur Max liked the aesthetic of the burnt tower, and decided to use it in the film.

The pomegranate that Sibylla feeds Balian after their first bout of lovemaking in a darkened room had to be digitally enhanced to be clearly seen among the muted colors.

There were 250 crossbows, 20,000 arrows, 3,000 shields, and 7,500 weapons made for the film.

Pope Urban III was said to have died from shock when he heard about the Battle of Hattin, depicted in the film.

There are approximately 800 visual effects shots in the theatrical cut of the film. There are roughly 1,500 in the Director's Cut.

Orlando Bloom suffered from a month of flu during the movie, and a couple of hand injuries from sword-fighting.

The first cut of the film presented to Fox executives was 186 minutes long. This had been taken from a 280-minute assembly edit (in the assembly, the actual siege itself was 45 minutes long). The main thing the executives questioned, was the subplot involving Sibylla's son, as they felt this was Balian's story, and his story didn't need that particular plot line. Indeed, even during pre-production itself, executives had ordered William Monahan to write a version of the script without the Baldwin V plot, and Ridley Scott shot the film in such a way, that the plot could be easily cut.

Production Designer Arthur Max used a real kasbah when constructing Ibelin, and simply built an "extension" onto the existing structure, as he had done in Huesca, Spain, near which he built the small French village seen at the beginning and end of the film. The set was built primarily by local craftsmen using traditional building techniques (i.e., mud bricks were made on-site from local earth and straw, doors and window frames were hand-carved from local palm trees, roofing tiles were hand-thrown and hand-fired).

William Monahan's first draft of the script was 186 pages. Executive Producer Lisa Ellzey was worried that, when such a large script was submitted to Fox for budget approval, the studio would balk at the length, so she called what she refers to as a "parenthetical meeting". According to Ellzey, almost every piece of dialogue in Monahan's script was preceded by a parenthetical description of how the lines should be spoken. She removed every single parenthetical (much to Monahan's chagrin), and thus managed to get the page count down by twenty pages, before sending it to Fox.

Ridley Scott and Cinematographer John Mathieson used the work of Artists David Roberts and William Turner for visual inspiration.

The chain mail for the film was made by the Weta Workshop, which also made the chain mail for The Lord of the Rings trilogy.

The set used for the Kerak courtyard, was actually shot on the northern wing of the Jerusalem set. By shooting at the opposite side, the production managed to save about five million dollars.

For the scene where the Templars attack the caravan in the desert, 143 extras, 60 military personnel, 125 horses, and 60 camels were used, with the same stunt riders portraying both the Templar attackers and the Saracen victims. For the Battle of Kerak, 400 extras and 200 horses were used.

Final film of Jon Finch. He died on December 28, 2012, at the age of 70.

Orlando Bloom was cast for this movie the day after he finished shooting Troy (2004) .

Hans Zimmer was originally attached as the film's Composer, but was replaced by Harry Gregson-Williams. A few weeks after this, the opposite occurred for another film: Zimmer replaced Gregson-Williams for the scoring duties of Madagascar (2005).

The movie was not cut on film, but was instead cut using a Digital Intermediate (the first time either Ridley Scott or Dody Dorn had ever used a DI). Originally the plan was for only the siege to be cut via DI, but due to the level of complexity in the editing, and the fact that so many things were changing so often, it was felt prudent to cut the film using a DI, rather than the original negative.

Officially, the opening scene, "The Crossroads", was the first scene shot, on January 12, 2004. The little short of Godfrey's flashback, was shot unofficially, two days earlier. Balian's fight with the cavalier over the horse, was the very last scene to be shot.

Production Designer Arthur Max, Set Decorator Sonja Klaus, and Costume Designer Janty Yates all visited the Salles des Croisades in the Musée National du Château de Versailles for inspiration about the period in which the film is set. The paintings found there became vital in helping the filmmakers design the flags, banners, horse dressing, costumes, etc. Max also used the work of Jean-Paul Jérôme and Paul Gustave Doré as inspiration in designing the film's sets.

"Vide Cor Meum", the song during King Baldwin IV's death scene and funeral, first appeared in Hannibal (2001) (also by Ridley Scott), while Dr. Hannibal Lecter and Inspector Pazzi see an outdoor opera in Florence, and was specially composed for the movie.

William Monahan was brought to the attention of Ridley Scott by Scott's associate, Lisa Ellzey, during production of Scott's previous film Matchstick Men (2003) with a script titled "Tripoli", intended to be a Russell Crowe vehicle. Scott would work on Tripoli in the evening after shooting "Matchstick Men" during the day. He and his team would then have story meetings all weekend. Indeed, "Tripoli" had effectively gone into preproduction. All the department heads had been appointed, Branko Lustig was working on a production schedule and budget, the major roles were being cast, design and artwork was bring done, models were being built, locations had been chosen and some of the set was actually being built. The film was even greenlit twice, but on both occasions things fell apart. It was around the time of the second collapse that Monahan delivered his "Kingdom of Heaven" script. Scott had always wanted to make a Crusades movie, and much of the ideas and metaphors from "Tripoli" were incorporated into "Kingdom".

In some shots, Orlando Bloom's wig looked a little patchy, so his hair had to be digitally filled in.

Two practical trebuchets were built for the film. The arms could pivot 56 feet (17 meters) and fire loads of 100 pounds (45 kilograms) approximately 1,312 feet (400 meters). During filming, the arms of one of the towers snapped, due to the extreme temperature changes that dried the wood in the arm. The snapping of the arm can be seen in the behind-the-scenes footage on the 4-Disc Director's Cut DVD.

Saladin was virtually forgotten by Muslim history until recently. His name was kept alive by European historians and novelists, who saw him as a heroic and honorable enemy in the Crusade stories. His appearance in popular adventure stories by the likes of Sir Walter Scott, made Muslims re-evaluate the long-forgotten Saladin in the nineteenth century, although they largely maintained the westernized, romantic, and largely fictitious character of western literature, including keeping him as an Arab hero, even though he was a Kurd. In the twentieth century, he has become a huge historical figure in Islam, mainly because of what his conquest of Jerusalem now represents for anti-Zionists.

Ridley Scott's first project at Fox since Alien (1979).

Marton Csokas, Paul Bettany, and Goran Visnjic all auditioned for the role of Balian.

The little toy soldier on the horse prop, seen in the extended version, now belongs to Lisa Ellzey, who keeps it on her office desk.

WILHELM SCREAM: During the climactic battle, when the Muslims cross the first white rocks, and Christians fire for the first time.

There were about fourteen thousand costumes created for the extras, and 650 different flag designs.

Brendan Gleeson starred opposite Orlando Bloom in Troy (2004). Bloom's character Paris stole Gleeson's character Menelaus' wife Helen.

Godfrey's brother and nephew, played by Robert Pugh and Nikolaj Coster-Waldau respectively, would both go to star in Game of Thrones (2011). Pugh played a prominent wildling north of the Wall, named Craster. Coster-Waldau plays Ser (sir) Jamie Lannister the Kingslayer and is a main character. Iain Glen (King Richard) plays Ser Jorah Mormont in GoT. Alexander Siddig also appeared in "Game of Thrones" as the head of the Martell dynasty.

Several years after the film was made, the black-and-silver coffin used in the film, was rescued from being thrown out (with permission) by a casual props man working on another project at the studio. The coffin was then moved to Kentwell Hall, Suffolk, where it is occasionally on display (but not described). During Tudor re-enactments at Kentwell Hall, if the coffin is on display, it is presented as a reliquary. Reliquaries were known to have existed locally before the dissolution of the monasteries and subsequently, but the presence of a reliquary in a public room of a manor like Kentwell would be unlikely (although there is some historical evidence that the manor may have stored local reliquaries for safe keeping at various points in the sixteenth century).

High winds in Morocco were a constant irritation to the cast and crew.

At any given time during production, there were seven different departments working separately, as off-shoots of the Props Department: the Smalls Department (kept all the small props together), the Drapes Department (made anything involving fabrics), the Dyeing Department (aged props as needed), the Paint Department (painted the props), the Model-making Department (made anything that could not be built to scale), the Leather Department (made anything of leather), the Woodwork Department (made all the furniture and wooden props), and the Metal Work Department (made all metal props).

The "Posta di Falcone" guard that Godfrey teaches Balian is in fact an actual term from the historical fencing treatise by Fiore De Liberi. Several copies of this manuscript, entitled either "Flos Duellatorum" or "Fior di Battaglia", survived to the present era and they were written in sometime between 1400 and 1409 A.D.

When Sibylla shows Balian the rings she wears, and explains where she got each of them, she points to one particular ring and says that this one came from France, and that she's never been there. In real-life, Eva Green was born and raised in Paris.

David Thewlis and Brendan Gleeson appear in the Harry Potter franchise.

This film stars two actors who were in Batman franchises: Liam Neeson, who starred in Batman Begins (2005) and The Dark Knight Rises (2012), and Jeremy Irons, who starred in Batman v Superman: Dawn of Justice (2016).

Liam Neeson also played a knight in Excalibur (1981) and Star Wars: Episode I - The Phantom Menace (1999).

Despite Saladin being portrayed by an Arab actor, he was actually of Kurdish descent.

According to journalist Robert Fisk, at several screenings in Beirut, Muslim audiences rose to their feet and applauded during the scene where Saladin (Ghassan Massoud) picks up a fallen crucifix and places it back on top of a table after the siege of Jerusalem has ended.

Several alternative endings were shot for the film. Orlando Bloom's preferred ending was as Balian rides past the pilgrims as they leave Jerusalem, he doesn't see Sibylla (Eva Green), but returns to France alone and resumes his life as a blacksmith. In another version, he does see her, and they speak and ultimately take one another hand's, and the film ends with them walking away into the desert with the other pilgrims. In another version he sees her, they talk, and then we cut to him arriving in France alone.

For the final scene, when Balian runs his hand along the sapling planted by his wife, and sees that it is starting to bud, a subtle digital effect plays a pivotal role in the shot. The plant used in the scene had no buds, so all the buds are one hundred percent CGI.

During the scene in which Balian is attacked by Guy's assassins, the accompanying music is an amended version of a track from Graeme Revell's score to The Crow (1994).