John Anderson's wife had recently died when he worked on this episode. He later described his role in this episode as one of the hardest he ever had to play.
The phantom ship is said to have been hiding at a "Lagrange point" behind one of the moons. This is a location where an object can be held in balance within the influence of the gravity of a planet, star or other large mass. Because of the balance of opposing forces, the object can stay in that point indefinitely without expending any power to maintain its position. For a real-world example, this is how the James Webb Space Telescope is positioned.
First appearance of Troi's teal uniform with the skirt.
John Anderson (Kevin Uxbridge) played California Charlie in Psycho (1960) while Anne Haney (Rishon Uxbridge) played Eliza Chambers in the remake Psycho (1998).
John Anderson played another role where his character was involved with a music box, 14 years before this one. In 1975, he played Amos Pike in the Little House on the Prairie episode Haunted House (1975), a man so broken by grief that he holds onto a music box to aid in his delusions. The box's music plays a large role in both stories.