Factual error: Bullets thrown (or spat) into a fire do not go off with a bang, and do not fly off and hit anything. The sound of a gunshot is produced by contained gases exploding out of the gun barrel. The casing of a bullet is far too weak to contain the gases, and would split as soon as the powder started to vaporise in the heat of the fire. You'd get a lot of smoke, a lot of fizz and pop, but no gunshot, and no bullets whizzing about.
Continuity mistake: In the scene after the first real battle of two tribes, the winning chieftain is about to chop off the heads of his enemies and is stopped by Sean Connery and Michael Caine. The chief threatens to lop off the head of the Connery character and is hit across the hand with the arrow he is carrying. The arrow breaks and pieces can be seen to fly off. In the next shot of Sean Connery the arrow is back in one piece.