When Michelle and King visit Rico at the Hospital Rico calls King sir and "Sarge" many times. King being a Staff Sergeant would not and cannot be called "sir" the title is reserved for officers only in the U.S. Army. He can only be called Sergeant, Staff Sergeant, and other variations of Sergeant.
After Sgt. Kings flight from base after receiving his stop loss, he pulls his jeep up to a small house surrounded by a rickety wooden and wire fence. As he begins to jump the fence, the camera cuts to a new angle and the fence miraculously changes to a much sturdier (and taller) chain link fence.
When Sgt. King steals Steve's jeep the top is down. Sgt. King is in a hurry, yet when he shows up at his destination in the next shot, the top of the jeep is up. Jeep tops take at least 10 minuets of tedious work to put up, and it was sunny all day, so it could not have been put up due to rain.
In the opening scene during the chase Tommy is on top the Humvee but after they chase the attackers into the ally and Brandon tells Frank and Randy to cover them. You never see Tommy come down from the top of the Humvee.
While Michelle and King are on the run King gets a cut on his forehead and places butterfly strip bandages on it. The amount of blood on the bandages and the skin around them changes during a single scene several times, going from heavy to light and back again.
During the ending sequence when Staff Sergeant King is "counting heads" on the bus, we see the newly-enlisted brothers of "Rico" and "Tommy". Staff Sergeant King was slated to return back to Iraq at the end of the month, however, if the ending sequence was the actual time that King was to return, the brothers would still be in boot camp, as Army Recruit Training is 9 weeks long, not including the Advanced Individual Training which follows Recruit Training.
The M4s shown in the film have the A2 style upper receiver, with fixed carrying handles. Only the first production run of M4s were built to this configuration, while the remainder had the A3 style upper receiver, with detachable carrying handle. The first production run M4s were a rather uncommon sight, and certainly wouldn't be used by a unit so up-to-date and well equipped as one shown in the film.
The M4s carried by soldiers in the film are shown firing on full auto. In reality, only select units, such as Special Forces and the Rangers, have this feature available to them. The standard issue M4 (as well as M16A2 and M16A4) is limited to three round bursts.
The RPG-7, used in the opening fight, shoots a rocket with a booster charge at an initial velocity of 150 m/s. This comes with a cracking sound stronger than a rifle shot and a smoke and fire jet from the back of the pipe to counter the recoil. At a safe 15-20 m from the operator, the rocket engine ignites and further accelerates the rocket to almost the speed of sound. There is no time to react with anything more than a startle response, let alone shout orders and run for cover.
When Sgt. King is home in Texas and giving his speech, they pan the audience and show a gentleman wearing an American Legion cap with his "Medal" ribbons on the left side. It is against American Legion policy to wear anything on the left side of the cap. Ribbons, etc, shall only be worn on the right side of the cap. The only thing allowed on the left side of the cap is City and State embroidery, yet this cap was not embroidered.