The actor who played the F.B.I. agent, Jay Karnes, also appeared in Relativity (1999), which also involves Seven of Nine and time travel.
The Starfleet therapist that Jean-Luc Picard imagines is wearing a never-before-seen uniform variant. It features the combadge style introduced in 2371 (Star Trek: Generations (1994)), and the same colors introduced in 2373 (Star Trek: First Contact (1996)). however, it lacks the quilting on the shoulder yoke and the seams and material are noticeably different. Whether this is a result of it being a figment of Picard's imagination, or it is meant to represent an actual style of uniform that had not previously appeared on screen, is unknown. The series has already established a different set of uniforms in service by 2382, another by 2399, and yet another by 2401. If this is indeed a real style of uniform, it is the fourth style introduced in the series.
The glass that Guinan drinks from to summon Q is the same type that she used to prepare a Tzartak aperitif in Time's Arrow (1992).
The Starfleet therapist is played by James Callis who portrayed Dr. Gaius Baltar on Battlestar Galactica (2004). This makes him the second Baltar to appear in Trek; John Colicos, who played Count Baltar in Battlestar Galactica (1978), had appeared as the first significant Klingon character, Kor, in Errand of Mercy (1967), and later reprised the role in three episodes of Star Trek: Deep Space Nine (1993).
The name of the FBI agent who is investigating extraterrestrials is Wells. This is most likely an homage to H.G. Wells, author of numerous acclaimed science fiction works including "The Time Machine".
Sunny Ozell: Patrick Stewart's wife is the singer in the nightclub when Dr. Jurati walks in. She is singing a song from her latest album.