The boy whom Willie was going to kill couldn't have been one of the eight because Russell died before the boy was even born. It is clearly explained, however, that the killer chooses Aidan because he was born immediately after one of the the eight surrogates died. The killer is concerned that the dead man was reincarnated as Aidan, so he (the killer) intends to kill Aidan just in case.
In the outside shot of the unsub's motel in Pensacola, Florida, the sky is black as if it's on a sound stage.
When Russell Smith dies, supposedly in 1988, the computer monitor that shows his heart rate is from the mid-to-late 1990s.