I remember this scene from when I was a child and saw it in the movie theater. In a scene where the Vietnamese soldier is shooting at Rambo across the gorge. Rambo takes out his bow and arrow and shoots the soldier. The soldier blows up, but it is very clear that his boots remain in place. Evidently the dummy's boots were mounted on a stand to support the dummy as it stood there. When the dummy blew up the shoes remained.