Opens with the quote, "To kill Koschei the Deathless, first you must find his soul, which is hidden in an egg, in a duck in a lead chest buried beneath an oak tree" from the Russian fairytale "The Death of Koschei the Deathless"
Potassium iodide saturates your system with iodine and prevents the thyroid gland (which uses a lot of iodine) from absorbing the radioactive isotope of iodine. That isotope is a significant product of uranium and plutonium fission. While it protects you from absorbing radioactive iodine, it does not protect you from the kind of ionizing radiation emitted by say a radioactive corpse.
Sasha Roiz's parents are Russian-born; he grew up speaking Russian, which the writers learned and decided to use.
At 10:10 a character enters room # 309 representing season 3 episode 09.
As Nick takes the bag to the guest room, he says, "Nah, I just, uh, gotta put the room in the bag".