This episode was directed by Robert Duncan McNeill, who played Tom Paris in Star Trek: Voyager (1995).
This episode marks the first chronological appearance of a tribble in the Star Trek saga. It is also the only appearance of a tribble in Star Trek: Enterprise (2001).
The containers carrying the Denobulans' rock samples were actually spacemaker pencil cases used by school children.
The style of backpack used by the Enterprise crew members in the caves was the Boblbee Megalopolis backpack.
This takes place in 2153.