Clark Gregg reprises his role as Coulson from the film series , and is joined by series regulars Ming-Na Wen , Brett Dalton , Chloe Bennet , Iain De Caestecker , and Elizabeth Henstridge . The episode draws comparisons to the plight of first responders to the September 11 attacks by showing firefighters ( with guest star Vincent Laresca playing one ) dying as a consequence of responding to the Battle of New York , as seen in '' Marvel 's The Avengers '' . The episode also features a major skydiving sequence , realized by combining live footage with CGI , as part of the development of the characters Fitz and Simmons , who received their own musical theme for the episode . It also sees Titus Welliver reprise his S.H.I.E.L.D. agent role from the Marvel One-Shot short films
September 11 attacks
September 11 attacks
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