Despite its serious flaws, the film is carefully crafted to offer a wealth of emotionally satisfying moments for fans of the 21 previous films in the Marvel Cinematic Universe — in particular, the older franchises of "Iron Man," "Captain America," "Thor" and "The Incredible Hulk" (with quite a bit of a newer franchise, "Ant-Man," referenced for good measure).
Since 2008, as we’ve progressed from “Iron Man” to “The Incredible Hulk” to “Thor” to “Captain America: The First Avenger,” we’ve seen Tony Stark (Robert Downey Jr.), Steve Rogers (Chris Evans), Bruce Banner (Mark Ruffalo), Thor (Chris Hemsworth), and Natasha Romanoff/Black Widow (Scarlett Johansson) and Clint Barton/Hawkeye (Jeremy Renner) battle alien invasions, terrorists, and ghosts from their past.
With the onerous task of having to bring matters to a close in the grandiose conflict between uber-villain Thanos (Josh Brolin) and the Avengers, directors Anthony & Joe Russo ( Captain America: Winter Soldier/Civil War ; Avengers: Infinity War ) summon the super-powered roster of characters that have accrued over a staggering range of 21 films since Iron Man and The Incredible Hulk kicked off the super-franchise way back in 2008.