(at around 21 mins) When Reaper sees 'Lucy' in the laboratory, his earpiece switches sides from right ear to left ear when the shot changes from his close up to showing him and his sister.
(at around 1h 5 mins) When Reaper, Sarge and Sam are watching the video file from UAC's human subject test, the time-code on the screen first starts out at 2:23. After a quick shot of all 3 actors, the timer then reads 2:33, then 2:34. It then instantly switches to 3:24 without any apparent fast forwarding of the video. After another quick shot of Sarge, the timer then starts at 2:27.
(at around 32 mins) When Sarge and Destroyer hear something in the vent above them, bullet holes can be seen in the duct to the right of the grate. The holes disappear when Destroyer moves to open the grate and reappear after Sarge and Destroyer shoot the duct full of holes.
(at around 42 mins) When Goat is brought back to the lab after being attacked his heart stops and Reaper tries to defibrillate him. Defibrillators do not restart hearts that have arrested completely, they are used when a heart has an abnormal rhythm, such as beating too quickly, to shock them back to normal.
(at around 1h 28 mins) When Sarge asks Reaper how much ammo he has left, Reaper replies that he has "half a clip." The correct term is magazine (usually abbreviated to "mag.") Any Marine would know the difference between a clip and magazine.
Although this may be the case in reality, the Doom games refer to small quantities of bullets as clips; (e.g. 'picked up a clip') calling it a clip in the movie was probably intentional in order to be more consistent with the game.
Although this may be the case in reality, the Doom games refer to small quantities of bullets as clips; (e.g. 'picked up a clip') calling it a clip in the movie was probably intentional in order to be more consistent with the game.
(at around 15 mins) When Portman and Goat check the chemical levels in the airlock, Portman mentions magnesium, chromium, and lead. We see his "chemical detection" device, and in the order he stated, follow the symbols Mg, Cr, and Ld. The symbol for lead is not Ld, but Pb. However, this is not necessarily a goof, since the device is not labeled as a Periodic Table, and the display may be "dumbed down" for common usage by lay people. "Ld" is a reasonable abbreviation for Lead for people without a chemistry or Latin background (Latin for metallic lead: Plumbum).
No Marine would ever refer to a sergeant of any rank as simply "Sarge." This is only done in the Army and the Air Force. However, this could be because it is the Sergeant's "battlefield nickname", considering several other members of the squad are also called by nicknames, and in fact, the automatic voice of his weapon says: "Handle-ID: Sarge" when he first picks it up.
(at around 1h 30 mins) When Sarge punches through the glass sign during the finale, pre-cut lines (making it easier to punch through the glass) are visible on its surface.
(at around 1h 22 mins) When Grimm is in the first-person-shooter segment, he shoots his reflection in a mirrored steel panel and looks himself in the eye. As the camera representing Grimm's perspective swings away, his reflection does not turn with it.
(at around 3 mins) The hand held video game Duke is playing (Galaxian 2 by Entex) is meant to be played holding the game vertically, one side of the buttons control the ship, the other side the Galaxians. Duke is holding the game horizontally, playing both sides at once, while seeing the action sideways.
(at around 27 mins) When The Kid asks Portman for the "Game Face" Pills: when Portman drops the pills into Kid's hand, all but the 2 that drop out are glued securely inside the bottle.
(at around 1h 30 mins) During the fight between Sarge and Grimm, when Sarge spins Grimm around and throws him on the computer console, the console is made out of cardboard.
(at around 45 mins) When Samantha is doing an autopsy on a creature and the light flickers you can see a hand on the light as the camera zooms out from a close up of the creature. It turns the light off and then disappears.
Since guarding the gateway is the priority, why doesn't Sarge simply leave most of his forces in the gateway room and use a small force to search the facility? After all, his decision not to do so precipitates the escape of the organism back to Earth the prevention of which was the point of guarding the gateway in the first place.
The helicopter the squad traveled in is a gunship, obviously not large enough for the interior compartment shown.
Throughout the movie, Sarge calls the Marines "soldiers." In reality, Marines are deeply offended when they are called "soldiers." Soldiers are Army.
(at around 48 mins, unrated version only) When Duke and Samantha are talking while she's examining the creature (right before he goes to get the power bone saw), he corrects her by saying the Marine term is 'Hooah,' when in fact it's 'Ooh rah'. 'Hooah' is an Army term, not a Marine term.
Reaper repeatedly addresses Sarge as "Sir." Sarge, like all the marines, is an enlisted man. Enlisted personnel are NEVER addressed as "Sir" in any branch of the U.S. armed forces (and most Western militaries, also). Also, at least once he refers to himself as the squad's "commanding officer," which is a specific term referring to an officer in command of a much larger entity, usually no smaller than a battalion, squadron, or ship. (This concept is rarely used correctly in movies and on TV; it's often incorrectly employed as a military-sounding term for anyone who is senior to another military member.) As the senior marine in the squad, his title would be "squad leader."
Goat blesses himself with his left hand; he should have used his right hand.