Powers Boothe's character previously appeared in The Avengers (2012) as a member of the World Security Council. Here, his name is revealed to be Gideon Malick.
The title is a reference to Fantastic Four #45 (1965), titled "Among Us Hide... The Inhumans!" which is the first appearance of the Inhumans Black Bolt, Crystal, Karnak, Lockjaw, and Triton.
This is the 50th episode of Agents of S.H.I.E.L.D.
To celebrate the series reaching 50 episodes, Marvel released a video showing cast and crew members discussing their memories and favorite moments of the series so far.
"Among Us Hide..." originally aired on ABC on November 3, 2015, and according to Nielsen Media Research, was watched by 3.84 million viewers.