Unfortunately, Loki always has a trick or illusion up his sleeve, as he suddenly appeared behind Coulson and stabbed him through the chest with his staff, killing the S.H.I.E.L.D. agent.
The groundbreaking movie saw Agent Coulson as a supporting character who meets a grim fate.
This is a not so subtle reference to Joss Whedon’s The Avengers.
While attempting to save Thor from Loki, Coulson cornered the villain with an impressive looking gun.