The real IED used in the Haditha bombing which sparked the incident was made from 155mm artillery shells and explosive-filled propane tanks. But the IED shown in the film uses grenade cartridges and a propane tank.
During the scene on the raid of the second house, the scene is shot from under a bed. A grenade is rolled into a room and the soldiers leave. When they return they start shooting. The shells that hit the ground are clearly blanks, as can be seen from the shell tips.
None of the U.S. Marines in the film are wearing any name-tapes on their camouflage uniforms, which is required for all USMC personnel.
All of the Iraqi Army soldiers in the film are seen wearing the "three-color" DCU uniform, although in the time period that the movie takes place in (late 2005), the Iraqi military wore the "chocolate-chip" DBDU uniform.
Most of the U.S. Marines in the film are seen with M16A2 rifles, although the M16A4 rifle had largely replaced the M16A2 in front-line USMC service by the time the movie took place (late 2005).
Some of the U.S. Marines in the film are seen with Colt Model 727 carbines, although that weapon had long been fully replaced by the M4A1 by the time the film took place (late 2005).
All of the U.S. Marines are wearing PASGT helmets, although in the time period that the movie takes place in (late 2005), the PASGT helmet had largely been replaced by the LWH helmet for front-line USMC personnel.