When Javi is threatening Driver in the cell after Driver saves the Kid and his Mother from Carnal, Javi's gun changes between cuts.
When Mel Gibson's character is driving the VW into the Port Mart parking lot driver's side shot reveals driver is wearing glasses yet Mel never wore any.
In the opening car chase, when Mel Gibson is driving the mercury, the instrument cluster is obviously from a late '90s GM truck.
During the police chase in the opening scene, the vehicle being driven is a Mercury Grand Marquis, but a ford emblem is visible on the trunk.
In the chase in the beginning of the film, the car tires squeal when making tight turns in the dirt. Tires don't squeal in dirt, only on pavement.
When the assassin's try to take out Mel Gibson's character he grabs one of the dropped pistols and fires back at the assassins. However, he holds the gun 'gangster style' on its side. He stated earlier in the film he had been in the Army at one point. No one with any weapons training would hold a pistol that way because they know it negatively affects shooting accuracy.
Mel Gibson's character says at the beginning of the film that his mom used to tell him, "F-ck off, loser." However, he later tells the kid that he was first put into prison when he was 14 for assaulting his father for beating his mom. The same mom who apparently didn't like him as a son.
During the chase at the beginning of the movie, tire tracks following a similar path can clearly be seen in the field as the cars near the Mexico border fence. Likely due to multiple takes when filming the scene.
The spoons on the two grenades had blue coloring. Blue indicates a training/dummy grenade.
When Driver crashes through the border fence into Mexico the car's trunk is shown clearly opened and empty.
When the Border Patrol agent shoots at Driver's car at the beginning of the film, his pistol does not cycle and eject any spent casings, indicating the pistol is obviously not real.
When the driver uses an angle grinder to cut open the damaged getaway car, it appears to be at the trunk or somewhere at the front lid.
An although there might be a secret stash build in somehow, there is no way to have enough room for a few sports bags between the metal sheets.
At least not unnoticed, as the car has been towed and searched.