Friendly Fire is the second episode of the sixth season. It was released on 2 October 2009.
The military scenario wherein a unit or troop is killed by weapons discharge from their own side (including allies). With modern forensics and ballistics there are presumably far fewer such incidents, pro rata, than in the past. History offers numerous examples of unpopular officers caught in such, as well as genuine accidents.
Near the end, during flashbacks to the gunfight from the beginning of the episode, the female agent is sitting on the ground with her back propped up on the front bumper of a car. Although the license plate is the same 4CIW600 number, some shots are of a plate with silkscreened MO and YR sticker boxes and some shots are of a plate with debossed MO and YR sticker boxes.
When Tina Gordon confesses to killing Ryba, she mentions he was hit by 28mm rounds from an FN P90. 28mm is more than an inch in diameter. The FN P90 fires 5.7mm rounds.
[This appears on the beginning of the episode] 1200 bullets fired 2 dead FBI agents 3 lies 1 truth