Good film, but some impossibilities exist in it:
1) At the beginning of the film, during training, Staff Sgt. Sykes accidentally kills one of his men in a live-fire drill as he fires a machine gun over their heads. Sykes is not investigated or reprimanded at all. In fact he goes on to lead a squad of men into battle. In real life Sykes would have most likely be relieved of his command, or at least demoted. Not to mention that Drill Sergeants that train Marines in boot camp would need to apply for transfer out of that duty to go into combat duty. The film makes it seem this type of transfer is commonly granted and even status quo; that the Marines have no need or interest in retaining Drill Sergeants for further basic combat training purposes. And if a Drill Sergeant did seek and was granted combat reassignment (which almost never happens) that Sergeant would probably never be assigned a squad that they had personally trained. NOT TO MENTION, machine guns are never fired with live rounds at recruits in basic training. Maybe in the BUDS training of Navy Seals, maybe. ALSO, Sykes constantly shouts profanities at his recruits in boot camp, which is officially banned nowadays, but wasn't always, but certainly was from at least 1989 forward.
2) Quite often it seems that the squad of men depicted in the film are the only troops around. They never seem to be part of a larger unit, like say a platoon or company. And Sykes doesn't seem to answer to a superior officer like a Lieutenant or Captain. The squad always seems to be secluded by themselves. We watch them carry on as the camera moves around them, and we never see any other troops or military hardware in the background, except in one or two short scenes. (No wonder they catch some friendly fire from some A-10s!) Meanwhile, all throughout the film, we are shown subtitles that count up the level of troops in the region, culminating at 500,000. I doubt that more than 50 troops were ever shown in any one scene in the film.
3) Marines are shown playing football in full anti-chemical suits in 112-degree weather. Most all the men would have collapsed and perhaps died because it is so hard to breath in gas masks, and full anti-chemical suits don't exactly "breath" either. They ain't made out of linen! Yet all we see is one Marine fall to his knees, which is played out as a comic moment.
4) When Swofford and Troy are in place to snipe at an enemy commander, Major Lincoln orders them to stand down, as he decides to call in an air strike instead. Troy, in frustration for being ordered to stand down, attacks and fights with Major Lincoln. Troy is not reprimanded or punished for this insubordination. Some form of reprimand would most certainly occurred in real life. I mean, Lincoln barely even yells at Troy!
5) After the scene described above, Swofford and Troy become separated from their squad. No one from their squad tries to locate them. Swofford and Troy are left to find their own way back to their squad, as if given up for dead. This would never happen in the real Marines.
6) At the end of the film, when Swofford and Troy do find their own way back to their squad, they find out that the war is over. Swofford complains that he never got to fire his rifle. Troy suggests he does so now. Swofford fires a round into the air. Other members of the squad follow suit and expend entire magazines of ammo into the air, with rifles set to full automatic fire (which most M-16's don't do, but rather fire in 3-round bursts instead). Random and pointless discharging of small arms in a non-combat setting is distinctly prohibited in all branches of the armed forces. Then they start burning their battle dress uniforms in a huge bonfire. No Sergeant would allow such anarchic and blatantly dangerous behavior, especially a former Drill Sergeant!!! Sykes does though, I guess since he doesn't seem to ever have a Lieutenant around to answer to. PLUS, they would still need their clothes and ammo since they were still in the middle of nowhere in the desert at night. Duh!
7) After the scene described above, it seems the troops go home the very next day! Impossible.
Okay, so not every scene needs to be perfect and by the book military-wise, as things do go awry in the fog of war. But this film is so not by the book you have to wonder if the filmmakers even knew the book existed!!!