Like virtually all movies about the events surrounding the Lincoln County War, John Tunstall (Terence Stamp) is incorrectly depicted as an older, sophisticated man. In reality, John Tunstall was only 24 years old when he was murdered. He was in fact younger than most of the Regulators. By contrast, Josiah "Doc" Scurlock (Kiefer Sutherland) was 31 at the time of Tunstall's murder and Richard "Dick" Brewer (Charlie Sheen) was 27. Only the youngest regulator, William H. Bonney, aka Billy the Kid (Emilio Estevez) was younger, being 20 at the time of the Lincoln County War.
Emilio Estevez was very depressed throughout the shoot because he had recently broken up with his girlfriend. One night, Lou Diamond Phillips decided to play a prank on him in an effort to cheer him up. Phillips had the wardrobe department put make-up on a sheep, dress it up, and put in Emilio's room.
In one scene Billy is reading a report that claims he is a lefty. To this he replies, "I ain't left-handed." This is a reference to films, books and media wrongly claiming Billy the Kid was left-handed based on the tintype photograph of him (tintypes produce a reversed image), making Billy look like he used his left hand to shoot.
In the scene where the men are going through the Indian Village (Spirit World), Kiefer Sutherland's character "Doc" is shown in the front of the group with a cover on his face, but it is not Kiefer Sutherland. He left that morning before the scene was shot, due to the birth of his child.
Lou Diamond Phillips stated in the commentary that he went to a meeting with the producers for what he thought was an audition. After explaining his character to him, he had thought they wanted him to act out a scene. After an odd pause John Fusco the producer said "well" - Phillips realized this wasn't an audition but they were offering him the part of Chavez.
Dialogue by Casey Siemaszko's character is sampled in the seminal 1994 hip-hop song "Regulate" by Warren G. and Nate Dogg, but according to the DVD commentary Siemaszko had no clue that this happened nor had he heard of the song itself.
In an impressive nod to historical accuracy, when Col. Nathan Dudley arrives at the siege of the McSween house with a detachment of cavalry, the troopers are correctly portrayed by African Americans. The U.S. Army was segregated at this time and New Mexico was policed by the 9th U.S. Cavalry, a unit composed of black soldiers under the command of white commissioned officers and black non-commissioned officers.
In the scene where Billy is having Doc write a letter to the Governor, Emilio Estevez wanted to make it look like he was making the speech off the top of his head, so the crew made a cue card for him to read. If you look closely, you can actually see his eyes moving while he is reciting the speech.
Charlie Sheen was reportedly a terrible horse rider. Throughout the shoot he couldn't keep his balance on the horse and fell off several times. After the shoot out with Henry Hill, his horse took off and he had no clue how to make it stop.
During the shoot out at the bar, the ammo blanks were packed with ceramic plaster for a louder sound. While filming the scene pieces of hot plaster were hitting the actors. Emilio Estevez was actually hit in the face, causing filming to stop for a short period while he got checked over. Dermot Mulroney was also shot in the shoulder blade.
The fight with Buckshot Roberts is broadly true to the historical record; however, there are some things left out. For starters, Roberts was in front of a small house when the battle started, not an outhouse. He also was shot and slowly dying from a gut wound he'd received from Charlie Bowdre's rifle at the beginning of the fight. Also Billy's attempt to take Roberts was almost successful. Billy counted the number of shots Roberts had fired and, figuring he was empty, charged the house doorway. Billy made it to Roberts himself and stuck his rifle in Roberts' face. But then Roberts slammed his own rifle butt into Billy's stomach and knocked the wind clean out of him. Billy rolled away from the house as Roberts retreated inside. It was inside the house that Roberts found the rifle he used to kill Dick Brewer by nearly blowing his head clean off. Roberts died from his wound the next day and he and Dick Brewer were buried at the site of the battle.
Contrary to the depiction in this movie, "Dirty" Steve Stephens survived the Lincoln County War. After the conflict he left Lincoln announcing his intention to relocate to Denver Colorado. From there, like so many of the minor players in the Lincoln County War, he simply vanishes from history. His ultimate fate and final resting place remain unknown to this day.
It is confirmed in an audio commentary by Lou Diamond Phillips, Dermot Mulroney and Casey Siemaszko that Tom Cruise has a uncredited cameo in the shootout at the McSween House. His face clearly appears on screen in slow motion when he is killed.
The term Regulators was applied to any private armed security force usually found in the employ of cattle, oil or railroad barons. Their primary function was to prevent the theft of their employer's property or, in a more sinister context, to serve as muscle to enforce their employer's will. They were most often veterans of the U. S. Civil War who either enjoyed that kind of work or simply had no other marketable skills.
A few members of the Hell's Angels Motorcycle Club were used as extras in the bar scene when the group goes to arrest Henry Hill. The members were also used as extra security during the shooting of the final battle due to the fact that crowds of onlookers were getting too big during filming.
In the final battle preparations Kiefer Sutherland had to put on a "squib blood pack" vest underneath his clothes. The rig was supposed to be triggered by Sutherland himself by pressing a hidden button. The whole rig took an hour to set up. When it was time to shoot the scene, Sutherland got on his horse and accidentally pressed the trigger, popping all of the blood packs. Setting the rig up again took another hour.
In the final battle at the end of the movie, Emilio Estevez (Billy the Kid) shoots Charlie Crawford. Charlie Crawford is the name of his brother Charlie Sheen's character in the TV series Spin City (1996).
James Horner wrote the film's original score but it was rejected for being too ethnic in Irish tone that the producers and director Christopher Cain wanted a more traditional Western score. Horner's score for this film has not been heard publicly.
The trivia items below may give away important plot points.
Dick Brewer gets killed by being shot in the stomach during the shootout with Buckshot Roberts. In reality, he had the top of his head blown off. However, everything else about the shootout is true to life, other than Doc being shot in the hand. This was actually George Coe who got his finger shot off.
When Murphy arrives at the siege of McSween's house, he is told that there are 30 men hiding in the house. While this number greatly exaggerates in the context of the film, thirty was closer to the number of Regulators that actually did take part in the Battle of Lincoln (the film depicts only five).
According to the documentary included in the special edition DVD, Casey Siemaszko's character "Charlie Bowdre" was a real historical figure who actually survived the gunfight at Alex McSween's house. He died in the movie; however, in real life he survived until a gunfight (at Stinking Springs, NM) that was depicted in Young Guns II (1990). After his own death, a mere 7 months later, Billy was laid to rest next to Charlie and Tom O'Folliard in the old Fort Sumner Cemetery.