Factual error: When the FBI tactical team arrives, they stay on the perimeter. They had not been told to stand down, and would have assaulted the White House and trapped the terrorists in a pincer movement with the SS attacking from the other side.
Factual error: The security booth is a hardened building and would not disintegrate like that from a RPG. It is made to withstand attacks.
Factual error: In the operations room from which the acting president (Morgan Freeman) is directing the crisis there are multiple uniformed military members at the table and seated on chairs behind the acting president. Over Morgan Freeman's left shoulder is seated a man wearing the uniform of an Air Force Senior Enlisted member (can't quite make out of the entire rank, probably a Chief Master Sergeant). The person portraying the Chief is way too old for the rank. On the other hand, a three-star Air Force General is depicted at the conference table and the actor is way too young to have three stars.
Answer: Forbes slipped up by mentioning the head bad guy's name. And, as good an agent as Forbes was, it is highly doubtful, not to mention suspicious, that he'd still be roaming around by himself this long after the fall of the White House. Plus Mike ain't stupid and most likely smelled a rat. And he was correct. Forbes was dirty.
Alan Keddie