Factual error: The U.S. army would never intervene in a hostage situation on American soil. Legally they're never be deployed for any reason on U.S. soil unless invaded by a foreign military. The F.B.I, S.W.A.T, state and local police agencies could have easily dealt with the events at the school.
Suggested correction: They could have been National Guard forces, called out by the Governor. However, the federal Insurrection act of 1807 does allow for The President to Federalize National Guard Troops and also call the US armed forces into service. This act has been invoked many times, the last by President George H.W. Bush in response to the 1992 L.A. Riots.
But the chances of the president deploying any type of military faction whether it be state or our military would be slim to none. Local agencies could have easily dealt with this.
Suggested correction: With the exception of a few scholarship students, the prep school students were the sons of the elite - wealthy and powerful, or "privileged" (e.g, bankers, major corporate heads, contractors, governors and even the Mafia). Even if they weren't part of the military-industrial complex, they make (and use) the rules to suit themselves. As the saying goes, rules were made to be broken. Also, loopholes can be found that enable re-interpretation and re-application to allow the use of the military.
And the heavily armed terrorists could be viewed as the functional equivalent of a foreign military, thereby justifying the use of the U.S. army.
Yep. Just like when the Army (eventually) responded to the insurrection at the Capitol in DC. As the first correction says, the rich and powerful do what they want and justify it later. Realistically, the audience would find it believable and doesn't care about the legal issues. This IS a valid legal mistake, but just barely a movie mistake.
