Patrick Stewart only appears in the final scene and only has one line of dialogue. He took time off to appear in his famous one-man version of "A Christmas Carol" in London while the episode was filmed.
The Barkonian moon reflected in the window (when Data looks outside) is Earth's moon rotated 90 degrees counterclockwise.
This episode was nominated for an Emmy Award for Outstanding Individual Achievement in Art Direction for a Series.
The title refers to a quote from William Shakespeare's Hamlet: "This above all: to thine own self be true, And it must follow, as the night the day, Thou canst not then be false to any man."
The events of this episode resembles the Goiania accident in central Brazil where there was an incident of radioactive contamination. The incident is depicted in Césio 137 - O Pesadelo de Goiânia (1990).