Some years after the death of Doc Holliday, Wyatt was quoted in an interview as saying, "Doc was a dentist, not a lawman or an assassin, whom necessity had made a gambler; a gentleman whom disease had made a frontier vagabond; a philosopher whom life had made a caustic wit; a long lean ash-blond fellow nearly dead with consumption, and at the same time the most skillful gambler and the nerviest, speediest, deadliest man with a six-gun that I ever knew."
The line quoted by Doc at the end of the fight at the O.K. Corral is historically true, and was reported in the Tombstone papers reporting the fight. When confronted by one of the cowboys at point blank range, the cowboy reportedly said, "I got you now Doc, you son of a bitch!", to which Doc gleefully retorted, "You're a daisy if you do!"
Doc Holliday's wink to Billy Clanton just before the culmination of the O.K. Corral gun fight was completely improvised by Val Kilmer.
According to Val Kilmer, screenwriter Kevin Jarre insisted the actors wear real wool costumes, in accordance with the time period. In the Birdcage Theater scene, Kilmer says a thermometer on the set read 134 degrees Fahrenheit (56 degrees Celsius). Kilmer suggested jokingly that was the reason Doc Holliday killed so many people. "It's just, like, he wore wool in the summer, in the Arizona territory, and that made him mad."
When the Earps first enter Tombstone, a grave marker in the cemetery says "Here lies Lester Moore, Four slugs from a .44, No Les No more." A real-life tombstone in Tombstone, Arizona, with that epitaph has been on display for at least 60 years. Lester Moore was a Wells Fargo agent murdered in Naco, Arizona in 1880 by Hank Dunston. Dunston also died in the fight and was buried in Naco.