Matt 'Axe' Axelson: Are Mikey and Danny really dead?
Marcus Luttrell: I don't know.
Matt 'Axe' Axelson: Are we dead?
Marcus Luttrell: Not yet.
Matt 'Axe' Axelson: We're good right?
Marcus Luttrell: Fuck yeah. We're solid.
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.
In the opening scenes showing the SEALS waking up, many photos stuck on walls of the SEAL's living quarters are shown. These photos contain some, if not all, real photos of the men killed on the mission. When the montage of the real-life men appears at the end of the film, you will recognise some familiar faces from the beginning of the film. Also, when Axelson is chatting with his wife Cindy (in the same 'waking up' sequence) on his laptop, the photo of Cindy on the right-hand-side of his laptop seems to be the real-life Cindy Axelson (if it isn't, then it's an actress who bears a very striking resemblance to her).