Syzygy refers to a conjoinment, and sometimes alignment. It has astronomical, psychological, medical, mathematical, even poetic connotations. In astronomy, the term means a unity created by the direct alignment of three celestial objects. In Jungian psychology, it references an alignment between (gendered) conscious and subconscious interests, that bring balance and mindfulness. In genetics, it is the pairing of chromosomes in meiosis.
A character references the upside down, an element from another Netflix original series, Stranger Things (2016).
The song playing at the club is Chto-to Osoboe Vo Mne ("Something special about me") by Russian band Shortparis.