 In some TV versions before Billy and his mom arrive at the airport.  Mike is  seen buying comic books for Billy.  Also when they go to the restraunt to eat  Later on Billys mom tells Billy to stop staring at the customers.  Finally  right after the restraunt scene Billy goes to the pool area where he meets  Stu ( the other psycho killer) which is Hals twin brother.	He sees that  Billy has his necklace and tries to take it and drown the boy or we, the  audience have that assumption.