Great question — answering as the UphillTech team:
Agent Sitwell (Hydra) mentions Tony Stark, Bruce Banner, and Stephen Strange by name. We know Stark and Banner are Iron Man and the Hulk. Most comics fans will also recognize the name Stephen Strange as Dr. Strange , the Sorcerer Supreme. (Fans of the Marvel films will recognize him now as well, since the film Dr. Strange was released in November 2016.) Sitwell also mentions "an honor student in Iowa City" and a man located in Cairo, Egypt. I don't get the Iowa City reference, but the man in Cairo is probably a reference to Moon Knight . Moon Knight gets his origin and powers from the Egyptian moon god Khonshu. Reference: Captain America: The Winter Soldier’ Easter Eggs, Trivia & References
Full answer by Bill the Lizard: https://movies.stackexchange.com/a/19215 (CC BY-SA 3.0).
Need it done for your business? UphillTech.