The Friendship One probe in this story is a thinly veiled approximation of the (appropriately named) Voyager I & II space probes launched by NASA in 1977. They also include records (made of gold) that have greetings from Earth in 55 languages including - no kidding - whale. There are also over 100 scenes of Earth and music from Bach to Chuck Berry. At this point in time, the probes are over 13 billion miles (21 billion km) from home, but still far from even one light year, which is 6 trillion miles (9.7 trillion km).
The unfinished ship-in-a-bottle of the USS Voyager built by Joe Carey and seen on Janeways desk at the end of the episode was actually a 1996 Hallmark Keepsake ornament which had been modified by production staff.
The music played by the Friendship probe and the little music box found by the away team is a passage from "The Four Seasons" symphony by Antonio Vivaldi.
This episode is the first chronological appearance of Joe Carey (Josh Clark) since State of Flux (1995), as his only other appearances occurred in time travel and alternate timeline episodes. Although unconfirmed, it is popular fan lore that the writers thought the character had been killed off due to a line mentioning his death in Before and After (1997) which was in an alternate, voided timeline.
Josh Clark appeared as a tactical officer aboard the USS Enterprise-D in the Star Trek: The Next Generation first season episode "Justice". Seven years later he portrayed the recurring character Lieutenant Joe Carey in seven episodes of Star Trek: Voyager. Given the time frames of TNG and VOY, it is possible that this unnamed officer is Carey, assuming a later transfer to Engineering division and departure from the Enterprise-D prior to 2371.