Picard tells the cadets about the events of Darmok (1991), where Picard encountered a race who called themselves the Children of Tamar. They communicated by speaking entirely in metaphor.
On the holodeck Picard mentions that it was still functioning, despite the Titan's power levels being dangerously low, because it runs on its own independent power system. This fact was first established in season one of Voyager. When the ship is first stranded in the Delta Quadrant, the crew looked into different methods of augmenting the ship's energy. In The Cloud (1995), Harry Kim experiments with tapping into the holodeck power grid, but each time he does it blows out an EPS grid. Both Harry and Torres come to the conclusion that the type of energy used by holodecks is incompatible with the rest of a starship's power grid.
The Archanis lager sign on the wall in 10 Forward is exactly the same as the one shown in the bar in Star Trek III: The Search for Spock (1984) when Dr. McCoy is trying to charter a space flight.
At approximately 10 minutes when Seven is searching for the changeling, a Vulcan strategy game, Kal-toh, can be seen on the desk. This was frequently played by Tuvok, Harry Kim, Icheb and even Seven once during the seven year run of Star Trek: Voyager (1995).
A picture of Odo appears on the tablet providing information about changeling buckets.