Wyatt wears a so-called Hollywood style pistol belt, which keeps the holster permanently positioned at his right side. Such holsters were not used in the Old West; they are a product of the movie industry. Actual gun belts of the period slipped through a loop on the back of the holster, which allowed the holster to be positioned anywhere along the belt's length. This correct type is worn by most of the film's other characters.
In the beginning of the movie, the Earp boys are in a cornfield. It is tall and green, and planted in rows, clearly the work of a modern corn planter. Corn in the mid 1800s would have been spindly, and planted by hand in "hills" not rows.
A sign on the side of a building advertised Clabber Girl Baking Powder. Although Clabber Baking Powder was a brand started in the mid-1800's in Terre Haute, Indiana, the brand wasn't named Clabber Girl until 1923.
In the first half of the movie after Wyatt marries his bride, they return to their new house following the wedding. When the front door is opened, you can clearly see a cold air return vent visible above the door frame inside the house. This goes with a forced air heating system, clearly not available in the 1800s.
When we see the telegram about Ed Masterson, it's written in block print letters and clearly with a ballpoint pens, which did not exist then. Telegrams were always written in cursive writing with a fountain pen.
During the performance of HMS Pinafore, an actor playing a British navy 'tar' is holding the Union Jack upside-down. The red angled cross has a larger white stripe below it than the one above it; the larger white stripe should be on top.
Wyatt Earp did not carry a Colt Peacemaker or use a conventional holster rig at the OK Corral. His preferred weapon was a Smith & Wesson American .44 (nickel plated and scroll engraved), which he carried in a holster hidden in a pocket of his full-length overcoat.
When the workmen are laying track for the railroad, a rail is dropped into place using rail tongs, then 2 workmen immediately begin hammering in the spikes. No one tries to measure or position the rail properly before attaching it to the tie. Plus, the end of the rail is right at the edge of the tie they are nailing it to, meaning the end of the next rail placed would be unsupported.
In the beginning of the movie (1865, the Civil War's end), the Earp family is sitting around a table talking about moving to California. Martha Earp is supposedly going to be staying in Iowa instead of moving with the family so she can marry Jimmy Jorgenson. Such a dilemma is moot as 10-year-old Martha Earp died in 1856, 9 years prior to this scene.
After Virgil is ambushed, he is shown lying in bed with the doctor removing shotgun pellets from his right arm. In real life, it was his left arm that was wounded and crippled for the rest of his life. This is due to the fact that the doctor had to remove several inches of shattered bone.
Wyatt carried a "Buntline Special", a Colt 45 with a 12" barrel. Four inches longer than a regular Colt, which made the overall length 18 inches. Five of these Specials were ordered by Ned Buntline for Wyatt, Charlie Basset, Bat Masterson, Bill Tilghman, and Neil Brown. These guns also came with a removable wooden stock, which could be attached to facilitate use as a rifle for long distance shooting. Bat and Bill cut off the extra four inches, but the rest carried theirs as supplied.Wyatt wore this Buntline special for the remainder of his career on his right hip, and a Colts frontier 45 , known as "The Peacemaker", with a 7 1/2" barrel, on his left hip.
This can be verified by referring to Stuart N. Lakes, "Wyatt Earp: Frontier Marshall: Pub 1931 Houghton Mifflin Harcourt,
'Bat' and Ed Masterson are claimed in the film to be the only two boys in their family. ('Only one measly brother?'). In fact, the Mastersons were a family of five boys and two girls. (Plus parents, of course. Also, it is unclear as to how many of the kids survived childhood.)
Johnny-behind-the-deuce is consistently referred to as "Tommy-behind-the-deuce".
This can verified by reading "Frontier Marshall-Wyatt Earp" by Stuart N.Lake, an authorized Biography of Wyatt Earps life. See Pages: 246,250,354,and 357.
When in the bar where Wyatt throws a pool ball at Ed Ross, Wyatt has a revolver tucked in his belt. It is still there when he straps Ed Ross's holster on his waist. When Wyatt & Sally go outside of the bar to watch the fireworks only his new holstered pistol remains.
When Wyatt, Ed, and Bat are shooting buffalo near the beginning of the movie, the buffalo are clearly dummies. When the last buffalo tumbles to the ground, its horns bounce up and down, indicating they're made from rubber.
During the final shootout of the Vendetta Ride in the canyon (which takes place in 1882), at 2:58:43, a Cowboy shooting at Wyatt Earp with a Winchester rifle has a modern wristwatch on his left wrist. Wristwatches weren't worn by men until British Army officers started using them in battle to coordinate actions a few years after this event took place, and they did not look like modern wristwatches, they were essentially a standard covered pocketwatch fixed to a leather strap.
In the film's first scene, Wyatt is shown sipping coffee in a darkened room. But the heavy cloud of steam coming from the cup indicates that there is no real coffee inside; actual coffee that hot would badly burn his lips if he attempted to drink it.
At the end of the film, Wyatt and Josephine sail to Cape Nome at the western tip of Alaska, by ship, and Wyatt makes a comment about there being "gold up in those mountains." The scenery shows trees and high snow-capped mountains which do not exist anywhere in eyesight of Nome. Gold dust in the Nome area was harvested from the ocean when it drifted onto the beach. The background looks more like the eastern Alaskan regions of Skagway, Juneau and Sitka.
The time line for the shootings of Virgil & Morgan Earp is "compressed" for the film. Both shootings are shown to take place on the same night, apparently only a few days after 26 October 1881. In fact, Virgil was shot and crippled on 28 December, and Morgan was shot and killed in March 1882, some months later.
The film depicts Doc Holliday killing Johnny Ringo in the final shootout of the Vendetta Ride. John Ringo was actually found dead in July 1882, several months after Wyatt Earp and Doc Holliday left the Arizona Territory. While it was widely believed to have been suicide, how he died remains a mystery to this day.