Special staff includes Kojima and 3 POW with the voice actor skill.
-Kojima can be found in the truck. See "Hideo Kojima" achievement. Then beat the main story.
- Do the Travel to Mine Base, then fulton recover the POW on the roof. He is kinda hidden by the area you start at. On the roof there should be a ledge that you can hang down on and scale across.
-On Zadornov Mission 1 look for the POW on Banana Fruta de Oro. Fulton him.
-Finally on Zadornov Mission 5 look for the POW near the truck at the start of the mission. Fulton again.