Benny's brother Davey was killed at age 8 according to Lenora but the tombstone Carol went to see has dates 1994 - 2000 which is 6 years.
When Benny sits on Christopher's bed after leaving the hot tub, he and his bathing suit are completely dry.
When first seen, Benny and his mom and brother are going into the store. Christopher and his mother are checking out. Then they drive out of the parking lot and hit Benny's brother. Benny's family should still have been shopping when Christopher's family drove out of the lot.