During the final argument, Don makes an insinuation that Maggie slept with Christopher Columbus, and she responds that she felt sorry for him because "he could have fallen off the end of the world". Contrary to popular belief, in 1492 nobody believed that the earth was flat anymore.
Dean is telling Sam about 2 "freaky" deaths that occurred in Prosperity, Indiana over the last 2 weeks. Online page seen regarding Carl Dunlop (@ minute 4:19) describes victims death was from " hypothermia," but the next line, & Dean, elaborates that the victim "boiled to death." The correct term should've read "hyperthermia," or heat exposure, since "hypothermia" is cold exposure.
After Dewey Stevens is killed via nail gun an officer states "We're still trying to figure out where they plugged in the nail gun". The nail gun is powered by air and plugged into the air compressor, it is the air compressor that was unplugged and required electricity not the nail gun.