Revealing mistake: When Morgan Freeman is about to take off in the helicopter to chase after the other two chasing Mr. Grey, one of the soldiers who is running to try stop him runs over a small pile of snow. The snow has a very unusual springing nature, obviously the springboard for the stunt, then as a result the soldier falls over.
Revealing mistake: When Beaver is fighting the alien in the bathroom, the cable operating it is visible.
Answer: Each of the 4 main characters; Jonsie, Pete, Beaver and Henry could communicate with one another telepathically. In addition to this power, Jonie also possessed a photographic memory. Pete could find or locate things. Henry could read other people's minds. Beaver had premonitions or some sort of sixth sense. He made a phonecall to Jonsie, knowing something was wrong and wrote ssdd on the phone booth.