Continuity mistake: The soldiers takes off from the aircraft carrier in Boeing CH-46 helicopters. In the next scene they are flying towards the target and the helicopters are magically upgraded to the Boeing CH-47 model. The mistake is clearly seen when counting the landing gear on the two types. The CH-46 has a single front landing gear and the CH-47 has a double landing gear in the front.
Other mistake: During the ending scene, when Samuel L. Jackson is walking away from the camera across the lawn, he passes directly between the platoon on the right practicing rifle drill, and the platoon leader giving them orders. Marines are taught to NEVER do this. It is called "breaking ranks", and a Colonel in the Marine Corps would have known this.
Factual error: During the "Vietnam Scene" at the beginning you see a very long take of an AK47 muzzle appearing slowly from a bush.The problem is, it has the slopping muzzle brake of the AKM, not the plain muzzle of an AK47. The AKM was not in service in 1968, and was never supplied to North Vietnam anyway.
Factual error: When Samuel L. Jackson stopped to salute the lowering of the flag, the first song of the Retreat Ceremony (Retreat) was playing. On real military bases, the flag stays in place during the first song while all military members are required to stand at Attention (unless they are in formation; which the person in charge will give the command of Parade Rest) and at the playing of the second song (To The Colors) the flag is lowered and they are required to salute.
Continuity mistake: In the bar scene Samuel L. Jackson presents Tommy Lee Jones with a case with the Mameluke sword and Lee's medals in it. There is a Silver Star in the case, but Tommy Lee Jones is not wearing one. Tommy Lee Jones is wearing a Defense Distiguished Service Medal, which is not in the case. The medals do look very similar though.
Factual error: In the US Embassy scene in the Ambassador's office, President Clinton and Vice President Gore's pictures are framed on the wall. In an US Embassy the President and the Secretary of State's picture are hung on the wall, not the Vice President. In this case the Secretary of State's picture should have been either Warren Christopher or Madeleine Albright who were the Secretary of States under Clinton.