Drive All Night Til Dawn - Agent Mack is signing along to a Henry Wagons song by this name at the beginning of the episode. Full disclosure: I only know this because Reddit told me so.
Barnroof Point, Colorado - This is an actual place in the southwest corner of Colorado, close(ish) to Navejo State Park.
Gravitonium - Obviously a reference to Graviton, this fictional element has the atomic number 123, which would place in the theoretical “g-block” of elements. These elements would be highly unstable and have extremely short half lives, so no wonder Quinn needed Hall’s help to stabilize the element.
Coulson’s Card Collection - Hey, did you know that Coulson DIED in The Avengers? Do you remember that he SACRIFICED himself while fighting alongside superheroes? And do you remember his collectable Captain America cards?
Ian Quinn - While Quinn’s a new character to the Marvel Universe, David Conrad, the actor who played him, does have links to Joss Whedon. The actor unsuccessfully tried to get the producers to cast him as an enemy of Buffy the Vampire Slayer several times over.