Damian tells Michael to shoot the container of gasoline with the C4 attached as they are fleeing down the river. That would not shut off. The explosive C4 is relatively stable. C4 can literally set on fire and it won't explode, so shooting it wouldn't set off an explosion. The detonator switch would have to be triggered for the explosion to happen.
While fleeing down the river on the boat, Damien asks Martinez. If she hasn't even seen before left, they prep some C4 with the trigger and taped it to a container of gasoline. The gasoline is not required, because that amount of C4 would have caused severe damage to anything in the general vicinity by itself.
During shoot out after capturing Kamali, when the enemy boat shows, one of bullets destroy Michael AimPoint (Reflector sight) but in the next shot, when Stonebridge is shooting again, he still have it on his gun.
Even though the action takes place in Colombia the Spanish spoken is Mexican.