This was Leonard Nimoy's final television acting role before his death on February 27, 2015 at the age of 83. Subsequently, however, he provided his voice in one animated film and in one animated video game, as well as in the major motion picture, Star Trek Into Darkness (2013).
Bell's freighter is reportedly enroute to a destination known as Talos. In The Menagerie: Part I (1966) Spock (Leonard Nimoy) and his former commander Christopher Pike head for the planet Talos IV. Talos was also the name of William Bell's cargo freighter ship.
The glyphs for this episode spell out: PURGE
At around 29 minutes, in the helicopter, listen to Nina's speech to Olivia, about how she is special, and has the ability to move between the two worlds. Although worded differently, it clearly has essentially the same "tone, and message" as the speech given to the Wizard of Oz's Dorothy, in her final moments before using her Ruby slippers to go home.
The three helicopters searching for William Bell's ship are Eurocopter AS-355 TwinStars which are a much less common twin turbine engine version of the popular AS-350 (now called Airbus H125) AStar.