This is stylized as a moving picture from the film noir genre, which was popular in the early part of twentieth century. By definition, film noir ("noir" is French for "black") is defined as a style or genre of cinematographic film marked by a mood of pessimism, fatalism, and menace. The term was originally applied (by a group of French critics) to American thriller or detective films made in the period 1944-54 and to the work of directors such as Orson Welles, Fritz Lang, and Billy Wilder.
During opening credits, on S.H.I.E.L.D.'s Wall of Honor (fallen agents) Agent J. Vertrees can be seen just below Agent D. Sousa, John B. Vertrees is the Art Director for the show since season 3.
The show opens up with a shot of the Hollywood Roosevelt Hotel. The hotel is noted not only for being the oldest continually operating hotel in Los Angeles but also for being a well-known haunted hotel.
The episode's opening sequence is an homage to Sunset Boulevard's (1950) "iconic opening of the dead body floating in a pool", with a title card that is a "throwback-style credit intro".
Enoch essentially served as a switchboard between the agents on the ground and the Zephyr. He seemed to have used an acoustic coupler to do so. Acoustic couplers were early modems used to transmit information over phone lines. The handset was placed on the coupler, and it would convert electric signals from the computing device into an acoustic signal or sound for the phone to send over the network.