Jenkins recites the quote, "Any sufficiently advanced technology is indistinguishable from magic." This is a famous adage coined by legendary Big Three science fiction author Arthur C. Clarke, and is known as Clarke's Third Law.
Stone says that Cassandra told them to take two lefts and a right. This is the same directions they were given by Mr. Franklin in And the Horns of a Dilemma.
The Rule of Three is part of Wiccan tradition, and is also called "The Threefold Law."
The necklace Cassandra is wearing is a Serotonin Molecule.
Christian Kane, Lindy Booth, and Alicia Witt have all made guest appearances on Supernatural.