Sam says that after Dean opened the tablet, every woman in her last month of pregnancy gave birth. Coincidentally, Jared Padalecki's wife Genevieve gave birth to their son during the filming of this episode.
(at around 29 mins) When Dean and Kevin are talking in the cabin, you can see Dean holding the prop they used as Death's sickle from a previous season.
In this episode, Meg calls Sam "Bullwinkle." Crowley has always called Sam "moose." Bullwinkle the moose was a lead character in the 1960's classic cartoon The Bullwinkle Show (1959).
Castiel tells Sam and Dean that when following a bee through the garden the plants showed him the way, he could see God's entire plan for the universe, and it was perfect and nothing needed added to it. Sam replies "except maybe some Thorazine". He is referring to one of the brand names for Chlorpromazine, which is an antipsychotic medication, it was actually the first antipsychotic approved for use and was released in 1950. There have been many new antipsychotic medications since then, including a new class called atypical antipsychotics that tend to have better effectiveness and fewer side effects. But Chlorpromazine is still widely prescribed, it used to be used to treat a number of mental illnesses, though currently it is typically used for schizophrenia and sometimes bipolar disorder when newer atypical antipsychotics are not effective.