Co-creator Dan Harmon can be heard voicing the Flu Hating Rapper in this episode.
Beth and Jerry are fighting Cronenbergs. Beth is using a pump action shotgun and jacks in a fresh round. A sexually aroused Jerry says "I wish that shotgun was my penis", to which Beth says "If it were, you could call me Ernest Hemingway" (but Jerry doesn't get the reference). Ernest Hemingway committed suicide with a shotgun; many folks mistakenly believe he stuck the barrel in his mouth.
Post-apocalypse Summer is entertaining Beth and Jerry by reenacting a scene from the 1975 movie "Jaws". The shark eyes speech is from one character describing the WWII sinking of the USS Indianapolis, where allegedly over 1000 sailors were in the sea treading water, and a rumoured hundreds of sharks attacked.
Davin and Beth leave the OR, entering a room with a horizontal line of colored flags overhead. Those are Tibetan 'Lung ta' (wind horse) prayer flags. All the decor items in that room are horse specific.
The title of this episode is a play on 'Love Potion #9.'