When Coulsons team heads to SHIELDs super-spy academy, Skye is wowed by the Wall of Valor in the lobby that lists the most heroic and courageous AHIELD agents who have fallen in the line of duty. Among those names is one James Buchanan Bucky Barnes, which Skye speaks aloud. For those who missed him in The First Avenger, Bucky is Caps sidekick in the comics, ally in the MCU and best friend in both. Hes also killed off in both only to be resurrected later on as...yep, you guessed it: The Winter Soldier, which rather conveniently premiered a few weeks after Skye intoned the nickname of one of its title characters. Come to think of it, after the events of Cap 2, shouldnt the Wall of Valor (if it even still exists) be scrubbed of Buckys name since he never actually bought the farm?