Gunfight at the OK Corral (1957)

Other mistake: When Kirk Douglas 'appears' to pull a knife from his collar and throw it into Lee Van Cleef's chest, you can see Kirk pick the knife up from a trough in the front edge of the bar. The knife is already in his hand when he reaches to pull the knife from his collar.

Visible crew/equipment: Toward the end of the movie, during the gunfight, Burt Lancaster hides behind an adobe wall. There is a bullet ricochet, and the wire & tape from the squib charge hangs out from the wall and bobs for several seconds.

Continuity mistake: Doc Holliday with the DOUBLE barrel shotgun shoots three times without reloading.

Dr. John 'Doc' Holliday: I'm a gambler. Money's just a tool of my trade.
Wyatt Earp: Of course, you will guarantee you won't lose.
Dr. John 'Doc' Holliday: I never lose. You see, poker's played by desperate men who cherish money. I don't lose because I have nothing to lose, including my life.

Wyatt Earp: Hold up your right hand. Do you solemnly swear to uphold... oh, this is ridiculous. You're deputized. Grab some gear, I'll get the horses.
Dr. John 'Doc' Holliday: Wait a minute, don't I get to wear a tin star?
Wyatt Earp: Not on your life.

Wyatt Earp: We'd like you to come to the wedding, Doc, - if it doesn't interfere with your poker.
Dr. John 'Doc' Holliday: I'm not good at weddings - only funerals. Deal me out.