In addition to learning that Supergirl is a faster flyer than her famous cousin, and verifying that Indigo is, indeed, a Coluan, the alien race that also produced Brainiac, last night's episode had a few Easter eggs that should have Superman fans buzzing. One in particular brings with it major implications for Supergirl's future.
The first classic comic item is seen upon Kara and Jimmy's arrival at the Fortress of Solitude. After she asks how they get into her cousin's home away from home, Jimmy uncovers a massive key, explaining that yes, Superman leaves it out in the open since it's "a million tons of condensed dwarf star."
Once inside, a second, even more important piece of DC Comics lore is revealed: a Legion flight ring.
Where Superman's key is a fun nod to classic comic stories, the ring's introduction is actually fairly significant. Not only does it add to "Supergirl's" ever-expanding incarnation of the DC Universe -- and answer the question of which show DC Entertainment CCO Geoff Johns teased would feature "a hint of the Legion" -- it gives us strong indication of where the character's adventures will lead future.
In the comics, not only does Supergirl travel to the 31st Century where she meets and becomes a member of the Legion of Super-Heroes, it's also where the character strikes up the defining romance of her life with fellow Legionnaire Brainac-5, a descendant of Superman's foe. What this will mean for the budding romance between Jimmy and Kara remains to be seen.
Of course, this isn't the first time we've seen the ring. It debuted several weeks back, as one of the fleeting images seen by Barry Allen as he raced from Earth-1 to Earth-2 -- a trip that also included, among other things, a glimpse of Supergirl. With Flash set to race into National City soon, and the hero seeing multiple images from an Earth other than his own, the DC Television Mulltiverse is expanding fairly rapidly.