The aria The Doctor sings in the teaser scene is Giuseppe Verdi's "La donna e' mobile" ("Woman is Fickle") from the third act of the opera Rigoletto. Legend has it that Verdi, afraid that the tune would get out before the premiere of the piece, withheld the aria from singer Raffaele Mirate until a few days before the premiere, and forbade him to sing, hum, or whistle it outside of rehearsals.
In this episode Robert Picardo wears the red command division uniform. This places him among the few regular actors who have worn all three colors, as he regularly wears the teal sciences uniform and, in The Swarm (1996), wore the gold operations uniform as the Alpha 11 Diagnostic program. He also wore yellow while playing the real Lewis Zimmerman in Doctor Bashir, I Presume (1997).
The nude portrait scene is a clear nod to Titanic (1997), both in its blocking and in Seven of Nine's pose, as well as the music and Captain Janeway's comment to Seven about the doctor "doing the hands well".
The alien spying on the Doctor is called Phlox. A few months later, the alien Dr. Phlox would star in Broken Bow, Part 1 (2001).
This episode introduces the Hierarchy species to the series. They return in The Void (2001) and Renaissance Man (2001).