Actor Allusion: Melinda May's mother states her agency hasn't fallen apart. She is portrayed by actress Tsai Chin, who played the undercover MI6 agent Ling in the James Bond movie You Only Live Twice. Also, they were mother and daughter back in the Joy Luck Club.
Glenn Morshower again plays a four-star Marine General.
Ascended Fanon: One of the biggest cases ever. Coulson's death being undone in numerous fanfics and such spawned this entire TV show.
The Cast Showoff: Both Clark Gregg and Ming-Na Wen have martial arts training and use it in the show.
Creator Couple: Jed Whedon (the younger brother of Joss Whedon) and his wife Maurissa Tancharoen are the showrunners of the series. note Joss himself has a significantly smaller role than most other Mutant Enemy projects due to being busy with The Avengers: Age of Ultron.
Dawson Casting: Inverted. The S.H.I.E.L.D. document about Skye being dropped off at her orphanage is dated 1989, which makes Skye a few years older than Chloe Bennet.
Enforced Method Acting: Brett Dalton noted on an interview with Marvel after "Turn, Turn, Turn" that he was informed that Ward would be revealed as a HYDRA agent near the ending of filming for "Yes Men", two episodes before the reveal. Assuming this was planned from the start, it means that he played Ward as an authentic good guy, making his deception more surprising when the time came.
Meanwhile, in an interview with HitFix before the season finale "Beginning of the End", Bill Paxton was informed he was Hydra right as he was hired, before anybody else on the set knew. So Paxton was allowed to play Garrett as a bad guy knowingly playing a good guy, and the rest of the cast were in the dark for quite a while... including Clark Gregg!
Fake Nationality: Englishman Ian Hart as Canadian Franklin Hall, Englishwoman Saffron Burrows as American Victoria Hand, and Irishwoman Ruth Negga as Americannote presumably Raina.
Fandom Nod: In "The Only Light in the Darkness" it's revealed the orphanage Skye grew up at named her Mary SuePoots. Skye had previously been accused of being a Mary Sue by detractors of the character.
Fan Nickname: A few have taken to calling the series "Interns of S.H.I.E.L.D.", due to the mostly college age-looking cast.
Col. Robert Hendry (Glenn Morshower) apparently survived getting blown up by Sebastian Shaw. He's also aged really well. Alternately, Special Agent Aaron Pierce went into the Marines and became a four-star general, just like in the Transformers films.
Jossed: When fans saw that the pilot involved an African American man with superpowers, many assumed that it was Luke Cage. Whedon, however, assured that it wasn't him. For good reason, because he's actually the Villain of the Week who later becomes Deathlok.
Name's the Same: "The Rising Tide", the hacktivist group Skye is part of, is also the name of a Real Life climate change activist group. The real life organisation Rising Tide is not pleased with the series using the name, since fans have confused them for some super hacker group (when in reality they're just a normal protest group).
"Melinda May" is also a song by Stephen Foster published in 1851.