Revealing mistake: As Liam Neeson looks at the money in the bag, he turns it over and it says "motion picture use only" on it.
Other mistake: Jim's truck is shown parked in a space in front of the Border Patrol building, and the spaces have those cement barriers that keep vehicles from pulling in too far (in this case, yellow ones). Then when Jim later pulls out of the space, he puts the truck in "Drive" and goes forward with no consequence. (00:25:06 - 00:27:11)
Factual error: The scope Jim is using is completely wrong (yes I know he tested the wind using dirt) but as a U.S.M.C. Marksman his scope would have had mil-dots on both the horizontal and vertical bars. (00:04:24)
Factual error: Jim is a former Marine and would never "chicken wing" the holding of that rifle the way he did. Even if that's the way he was taught back in?, over the years he would have learned and adapted the correct stance. (00:04:29)
Continuity mistake: Jim pushes down the corrupt cop to the floor, and his hat falls off. A shot later, it's back on.
Other mistake: Bad guy stands in front of a shop while the girl is in a red car. The shop has an "open" sign, and a customer comes out. Problem is it is Wednesday in the story line. The business has its store hours listed on door - it is closed on Sunday and Wednesday.