Factual error: During the performance of the Marine Silent Drill Platoon at the very beginning of the movie, they are performing with Springfield 1903 Rifles, whereas the Marines perform with M1 Garands. The reason is that the Texas A&M Fish drill team was being used in the Marines' stead.
Factual error: Danny is in his apartment watching a baseball game on TV between the San Diego Padres and the Atlanta Braves. The game announcer is Jerry Coleman for the San Diego Padres. Since Danny is in D.C., he would have been watching the game on WTBS TBS Superstation (an Atlanta TV station), and Jerry Coleman wouldn't have been announcing a San Diego Padres game on TBS. It would have been Atlanta announcers. (00:46:00)
Factual error: In the opening scene, during the overhead shots of the Marine band, the band members are out of step with the music. In military marching, the left foot ALWAYS falls on the downbeat of the music. In all other shots, the music is properly synchronised.
Factual error: The film's presentation of Guantanamo Bay seems unrealistic. In an attempt to make Jessep seem autocratic and akin to a dictator, they show a scene of Jessep and Danny meeting outdoors. In the background, there is a colonial-era type mansion in immaculate condition. There are no such buildings on the Naval base at Guantanamo Bay.
Factual error: The crime occurs on Friday, September 6 and the next week, as Kaffee and Weinberg are walking to Weinberg's house and discussing leaving for Cuba the next morning, the ground is covered with leaves and the trees are in full fall color. This doesn't occur in the second (or even the third week) of September in the Washington, D.C./Virginia area. This scene was shot much later, toward the end of October or early November, but it's supposedly well before trial, which is held in early October.
Answer: It'll be considered hearsay.