When in the mine, Dean says he has about 5 gallons of gas back at the car... When we see him at the car, he's pulling a 5 litre gas can out. AKA 1.3 gallons.
When Sam is explaining the weird situation they will soon be facing he tells Dean that the girl saw a mutant with green eyes. He shows Dean an article on his laptop where the story of the mutant is explained. In the article it reads the supposed mutant had red eyes, not green. The article also states that it was Kim that was taken and is still missing, yet Sam says otherwise and we see otherwise when Dean is talking to Kim about Libby missing.
At the end of the episode, Sam tells Dean that - as a kid - he used to be afraid when Dean and their father went off on hunts without him. He says he was scared they would not come back because a vamp, rugaru, or other monster had killed them. However, in the season one episode "Dead Man's Blood", it was revealed that the brothers had no knowledge of the existence of vampires in their youth.
When the boys are talking to Etta, they are discussing how her husband (she says it was her 2nd husband) went missing last time these monsters were here back in 1989. That was 27 years prior, as this episode takes place in 2016, and the story is these monsters show up every 27 years. They really missed the mark with the casting here, because the actress playing Etta is 41 in this episode, and doesn't look even that old. And so 27 years prior, she would have been 14 years old. Are we to believe a 14 year old was already on her 2nd husband back in 1989 when he went missing? I don't think so.