what reminder of the outside world do the boys discover? what might it signify?

I think you might be referring to the dead pilot in the parachute. He symbolizes the folly of mankind. With all of mans' technological capabilities, this pilot floats down a corpse. A reminder of the inherent flaw in man which Simon tries so hard to communicate. The beast exists in the greater world just as it exists in the boys on the island.

what reminder of the outside world do the boys discover in lord of the flies

what does piggy mean when he says that there arent ghosts cos things wouldnt make sense.