Plot hole: When Agent Memphis is about to be executed they ask him if he needs to "Piss" so as to not have government-used drugs in his system before he commits suicide. They even mention writing a suicide note for him. He's had seven shades beaten out of him though and was kidnapped whilst on the phone, mid-conversation and with possible witnesses. Surely if it wasn't the first time they had done this then they would have taken more care to make sure it wasn't a complete fake-out.
Factual error: When Swagger is fleeing from the police in the car wash after being shot, the radio says that he is at a car wash at 9th and Girard. There is no such intersection. On Girard Ave, 9th street picks up south and north of that street.
Continuity mistake: When Swagger is in the stolen FBI car at the assumed end of the car wash, we hear the wheels "peeling out" and the scene shows the back of the car, wet. Then, the scene quickly changes to the FBI car speeding out of the car wash completely dry with just a little water on the windows. (00:32:00 - 00:33:00)
Continuity mistake: In the beginning where Bob and Donnie are watching over the road waiting for the returning troops, the bolt of the M40 rifle Bob has at the ready is closed. In the shot right after Donnie pulls out the picture of Sara, the bolt is shown open, but appears not to be fully open. In the next shot of the rifle, the bolt is again closed. We do not hear the bolt, nor would a sniper at the ready fumble with an arm at the ready.
Continuity mistake: In the very beginning of the film when Swagger takes out the enemy's truck approaching friendly troops, the truck flips over onto its side and two pieces of the truck spill out onto the road, yet when the friendly troops approach/pass it the objects are nowhere to be seen.
Continuity mistake: Approximately 3 minutes into the film, the scene cuts from Bobby Lee Swagger and his scouter to the U.S. Camp in Ethiopia, you can see a truck pulling into the camp, if you watch closely from the beginning of this scene to the following overhead shot, there are a few changes, the U.S. flag on top of the camouflaged tent disappears, there are twice as many red barrels at the entrance to the camp than in the previous shot.
Other mistake: In a whole lot of scenes, Bob closes both his eyes when he fires his sniper rifle. This is a common and natural reaction when an inexperienced shooter fires a gun. An experienced hunter or marksman would never do that, and especially not a military sniper.
Continuity mistake: When Memphis is taken hostage his telephone falls on the middle of the sidewalk. In the next shot it lies on the edge. (01:06:30)
Factual error: When FBI agent Memphis is reviewing the assassination on video, you can hear the shot first and then see the blood spray of the bullet impact on the Archbishop. This defies physics as bullets travel faster than the speed of sound. Given the distance the sniper shot from, the sound of the shot would be be heard a second or 2 after the impact.
Factual error: Bob and Nick engage in a shootout in Lynchburg Virgina at night (according to FBI Howard), - although based on the day lighting it'd have been late afternoon - then call him from Bozeman, Montana, next day, around 1 p.m. based on the shadows, standing in front of the very same Dodge pickup. Even allowing for the passage of 18 hours, they would have had to average over 119 mph, not allowing for fuel stops, to get there.
Revealing mistake: When Gunny snipers the shotgun (and hand) off the bad guy in the snow covered mountains, his rifle is right-handed bolt, and he shoots right-handed except for the mountain scenes. He closes his right eye before he shoots, and it even shows a close-up of his left finger on the trigger, obviously a flipped shot.
Visible crew/equipment: About half way through the film when they go to see the old gun smith, as they get out of the truck and just after Swagger says "welcome to Tennessee, the patron state of shooting stuff" and closes the truck door, you can see a reflection of someone holding a board or something in the wing mirror.
Other mistake: If you look at the license plate on the government car that mark Wahlburg is driving, they are not government plates but regular Pennsylvania license plates. The next scene the driver tells the FBI guy that they are government plates which they are not.