* AlternativeCharacterInterpretation: The CruelTwistEnding can be interpreted two ways:
** [[spoiler: Dan never did rescue Mark White and only told Paul that he did to give him some hope.]]
** [[spoiler: Dan ''did'' rescue Mark White, and the insurgents [[FridgeHorror are entirely capable of reaching Paul's family]].]]
* NightmareFuel: Especially if you're claustrophobic.
* ParanoiaFuel
* TearJerker: Paul calling his mother only for the viewer to realize that she has Alzheimers and barely remembers who her own son is. It's just downright cruel.
** [[spoiler:So is him finally talking to his wife and hearing his rescue]]
* {{Woobie}}: It's difficult not to feel really bad for Paul, given that we spend the entire movie watching him panic, suffer [[spoiler:and eventually die.]]