Continuity mistake: As Tommy moves around the table to say good night to his father, Morgan has the cigar in his mouth and is about to light it. As Tommy gets hugged the scene changes to closer in and Morgan's cigar is down by his side, unlit. (01:13:00 - 01:14:00)
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.
