Towards the end when Banning meets with the President to offer his resignation, he takes out his Secret Service badge and places it on the table. In the next scene when the President gets up to walk around the table, no badge is seen.
An aide tells the Vice President that the transfer of power back to a president has never happened in our history. This is incorrect, on July 13, 1985 Ronald Reagan underwent colon cancer surgery while under anesthesia, Vice President George H. W. Bush discharged the powers and duties of the presidency during his incapacity, serving as acting president until later that day, when Reagan reclaimed his authority. President George W. Bush underwent a colonoscopy procedure on June 29, 2002, and again on July 21, 2007. Vice President Dick Cheney temporarily became acting president on both occasions then power was transferred back to Bush.
At six foot tall, or nearly 183cm, Nick Nolte's character would have been at least six inches taller and substantially larger than the average tunnel rat in Vietnam. It's exceedingly unlikely he would have served in such a role as he would not have been able to physically traverse the small, narrow tunnels that the Viet Cong used.
It's simply absurd to think a Special Agent for the FBI would start laying out all the circumstantial evidence against a potential suspect in an assassination attempt or his wife, revealing everything they supposedly had on them and she would not have the authority to charge him with crimes before he was read his rights or even been allowed to see a lawyer, and before any investigation was done at all while he is still in a hospital bed. There are strict procedures to follow. What she did would most likely get him off on numerous technicalities.