Ogdenville, Brockway, and North Haverbrook are names of towns that Sam mentions as locations where the Shtriga had previously attacked. These are also the names of the three fictional towns in 'The Simpsons', where Lyle Lanley conned the inhabitants into paying him to build shoddy monorails in the episode Marge vs. the Monorail (1993).
Shtriga - a monster in this episode - is mentioned to be Albanian, which is incorrect. In fact it comes from Slavic mythology (especially Polish folklore - 'Strzyga'). It is supposed to be a female demon somewhat similar to a vampire. The undead strzygas were believed to fly at night in a form of an owl and attack night-time travelers and people who had wandered off into the woods at night, sucking out their blood and eating their insides.
People with two hearts, two souls and two sets of teeth (the second one barely visible) were believed to be strzygas. A newborn child with already developed teeth was also believed to be one. When a person was identified as a strzyga she was chased away from human settlements. Such strzygas usually died at a young age, but, according to belief, only one of their two souls would pass to the afterlife; the other soul was believed to cause the deceased strzyga to come back to life and prey upon other living beings.
When a person believed to be a strzyga died, decapitating the corpse and burying the head separate from the rest of the body was believed to prevent the strzyga from rising from the dead; burying the body face down with a sickle around its head was believed to work as well.
Black River Falls and its township Brockway, Wisconsin are real places. Black River Falls had an outburst of deaths in the 1890's. There is a documentary about the disaster called Wisconsin Death Trip (1999) based on the book by Michael Lesy (1973). Both the book and the movie are constructed entirely from actual news reports.
The cartoon that Sam is seen watching during Dean's first childhood flashback is Thundercats (1985).
The series Supernatural was on the air so long that when the final episode aired, the actor who plays young Sam in this episode (Alex Ferris) was the same age the older Sam (Jared Padalecki) was when this episode originally aired, 23 years old