Continuity mistake: In the scene where Marcus is removing the shrapnel from his leg, when he gets to the last and largest piece, he places the medallion from his necklace in his mouth to bite down on. As the scene transitions from the leg to his face as it is removed, he appears to no longer have the medallion in his mouth. Then once the shrapnel is removed, he collapses and still has the medallion in his mouth.
Factual error: In the scene at the evacuation hospital doctors are seen administering shocks to Marcus Luttrell (Mark Wahlberg) with paddles. The EKG shows a flatline. In reality, medical personnel do not give shocks for a flatline - a "shock" is to correct Ventricular Fibrillation into a normal sinus rhythm, if you have a systole there is no muscle activity in the cardiac area and a manual shock will not achieve anything.
Continuity mistake: When the helicopters are coming to save Lutrell, the sky is blue with no clouds, but the view from the plane providing cover fire shows heavy cloud cover.
Character mistake: When Murphy calls his command, a Marine Staff Sergeant answers the phone as "Sergeant." Maybe in the Army, but a Marine Staff Sergeant would never refer to himself as Sergeant.
Visible crew/equipment: As the S.E.A.L.s retreat down the mountain, the camera crew is visible at rear, bottom right. Red optical mount and clean-face cameraman are a dead giveaway. (01:08:00)
Revealing mistake: When Mark Wahlberg removes the shrapnel from his leg, it is pretty obvious that it is a fake leg. If you look at and compare its dimensions to the rest of his body, you can see that that would be the leg of a giant man. The thigh is way too long, and the whole leg is way too big for his body. You can also tell by his body posture that his real leg goes into the couch he is sitting on.
Factual error: In many shots we see a Marc Lee memorial patch. Marc Lee was killed August 2, 2006. Operation Redwing was June 28, 2005, more than a year earlier.
Continuity mistake: Throughout the movie, the viewer sees multiple shots of the SEALs firing at the Taliban, then the shot zooms in to a through-the-rifle-sight shot. In several of these shots, the SEALs are quite obviously canting their weapons to the left or right, yet when the shot zooms into the sight, the crosshairs are perfectly level. They should be canted, too, if the rifle is canted while firing.
Factual error: During the final attack on the village by Apache helicopters, they are shown with front-mounted machine guns instead of the 30mm cannon. Apaches are not armed with a front machine gun.
Continuity mistake: In the final shoot out when the Taliban bad guy is coming up on the guy that saves Mark Wahlberg, there is a bullet wound on the back of the brown vest (top left, back left shoulder), but a few minutes later when he wrestles the Taliban leader that wound or blood stain isn't there.
Factual error: Throughout the film, the SEALs are seen wearing Mechanix gloves, but the type seen are the current type. What distinguishes them from older models is the velcro wrist strap. The older models had an elastic, velcro strap, while the newer ones have a reinforced, rubberized velcro strap. The newer type as seen in the film is inaccurate for the time period.
Continuity mistake: When the seal team are watching Taliban with binoculars in the village below, the range finder changes significantly when binoculars are passed from one member to another or Taliban are viewed again.