After the building explodes and Michael is calling Sam's name, the camera angle shows the fire and damaged building. Through a small opening in some casing, we can see Sam's light-blue shirt twice as the building is shown on fire before we see Sam come running with the man he has rescued.
When Anson is holding the detonator, after he tells Michael that his finger is on a deadman's switch, his finger is shown off and on the switch a few times.