In the confrontation scene on the piazza when Robert McCall is appearing from behind the columns and walking toward Vincent Quaranta one of McCall's two guns is empty (the slide is locked in the open/back position) and a moment later the slide is closed when he hands over the guns to Quaranta .
After the initial confrontation, McCall sits and puts the Beretta to his head and you hear the gun click, indicating the hammer dropped and the gun is out of ammo. When that model (92f) is out of ammo, the slide locks back, contrary to that scene. After firing rounds, that pistol's hammer would be back ready to fire the next round, contrary to the scene showing the lowered hammer. Finally, for the gun to make the clicking sound indicating the hammer dropped and the gun is out of ammo, McCall would have to pull the trigger, which he does not do. The sound was inserted in post-production to make the viewer believe McCall was contemplating suicide.
Toward the beginning of the film when McCall shoots Lorenzo twice with a powerful long gun, he holds it low, cradling it in his hands. Normally the gun's kick would send it flying out of his hands. The gun barely twitches.
The film is set in the fictional town of Altamonte, not Altomonte, a mountain village and not situated at the coast. The actual town where the movie was shot is Atrani, on the Amalfi coast.
In the opening confrontation in Sicily, there are 10 shots fired from a 6 shot revolver.
The Camorra don't seem all that concerned about the raid on the vineyard cutting off the drug supply and losing all the money stashed at the villa.
Emma Collins, a trained CIA agent, takes a photograph of McCall with the camera flash sound effect enabled.
McCall knows he has been shot from the back but wastes precious seconds and ammunition shooting in front of him.
McCall does not apply pressure on his gun shot wound despite being trained as a field medic.