Factual error: When Gene Hackman is shot at the end he looks down and sees the hole in his shadow. However if he was shot from someone at the same level as him, the hole would be straight, parallel to the Earth's surface. So if he could he the reasonably proportioned shadow the angle of the sun wouldn't show any hole in him at all.
Suggested correction: First, it is reasonable to assume that Hackman is significantly taller than Stone, and, given that she is firing from a hip draw the angle of entry for the fatal gunshot would be on a upward trajectory. This generally upward bullet trace combined with the evening or late day sun could be reasonably expected to cast a shadow if you suspend disbelief initially to allow that this type of wound is practically plausible.
The fact that she is shorter is irrelevant given the distance between them. For the angle of the light showing through him to make sense (and that's assuming it makes sense for it to show through him at all) she would need to be kneeling directly in front of him. The fact that, as you say, suspension of belief is required demonstrates the original mistake is valid.
Suggested correction: He doesn't see the hole in his shadow. We see him look downward slightly, then we see the shadow slightly from the side, not the view he would see. We then see him looking down at himself. It's easy to assume he is looking at his shadow, but we don't see him doing that. He could simply be staring into space, with the shadow presented for dramatic effect for the viewer.
Factual error: In the scene just before Harrod fights Ace Handlin, we see a view of Harrod's feet passing a blood stain in the dirt. This bright red color would be impossible when mixed with the dirt. Also we are led to believe that fights happen on the hour, each hour. The blood would have coagulated and been nothing but a dark spot on the ground. This has obviously been done to emphasize that the ground is bloody.
Factual error: In the first scene of the shoot out competition where Di Caprio is loading his revolver, the ammunition is modern headstamped R-P 44 Colt ammunition. This is modern 1990-2000 ammo.
Suggested correction: It is stamped 45, not 44.
Factual error: When Herod shoots Cantrell for the last time, the entry wound is roughly the size of a tennis ball in his head. There is no way a gun of that period could make a hole that big.
Factual error: In the bar when the lady buys herself a drink before getting challenged to her first fight, she drops a nickel on the table. It's a Jefferson nickel, not minted until 1913.
