J. Paul Boehmer, who plays an SS agent in this episode, also played an SS agent and the future Borg drone, One, in the Star Trek: Voyager episodes, "The Killing Game, Part I" & "The Killing Game, Part II", and "Drone", respectively.

This is the second episode of "Star Trek" based entirely in the 20th Century. The first was the Star Trek episode "Assignment: Earth", which took place entirely in 1968.

First Star Trek series that started a 4th season without having any change in the cast since it started, TOS never had a 4th season, TNG had already had two cast members come and go by the 4th season, DS9 had Michael Dorn (Worf) added to the cast at the start of the 4th season, and Voyager replaced Jennifer Lien (Kes) with Jeri Ryan (Seven of Nine) at the start of it's 4th season.