When Sam calls Dean on the phone, Dean immediately drops the phone. When it lands on the ground, the call time is listed as 13 seconds, even though only a couple of seconds have passed.
This episode takes place in Michigan. Michigan has never had the death penalty and was the first state to ban it via state constitution in 1836. One of the victims, Warren, was originally sentenced in 1981 and eventually released from jail. His death sentence occurred when he was tried by Osiris.
Before Dean leaves for the bar to continue the investigation, you see a Canada Post truck in the background behind Sam. The show is purported to take place in the United States.
It's established that a guilty person's executioner is determined by what they feel guilty about. By that rationale, Dean's executioner should have been Amy.