At one point during the private meeting between Wayne and Alan where they discuss Julie Purcell's apparent reappearance, Alan holds a glass of whiskey. A second later, the glass is on the table, yet the chinking of ice in the glass is audible, as though he is still holding it.
There is no Walgreens in Sallisaw, Oklahoma. They have a Wal-Mart but no Walgreens.
The date of the disappearance of the children has been established as Friday, November 7, 1980 (and also they may have been contacted by the killer on Halloween night also a Friday in 1980). When asked where he was that night, Lucy's cousin, Dan (the uncle of the Purcell children) said that he went to a bar and then went home and watched CHiPS on TV. In October/November 1980, CHiPs was broadcast on NBC on Sunday nights from 8-9 PM. If not a mistake in the writing, then the Detectives needed to question the character further about what he was watching on the night of the children's disappearance a it could not have been CHiPS.