It's Been a Long Day
When Tony gets a surprise visit from Nick Fury in the Bartons' barn, he explains that the assembled heroes have had a long day - "like, Eugene O'Neill long." The Pulitzer Prize-winning American playwright may not be widely known by modern audiences, but the line is likely a reference to his play "Long Day's Journey Into Night," following an American family through... well, a particularly trying day.
His Girl, Friday
When Tony is searching for a new A.I. to load into his armor for the final fight (since JARVIS has been used to create Vision) he selects 'F.R.I.D.A.Y.' for the job (voiced by Kerry Condon). The classic film His Girl Friday (1940) has been mentioned by writer/director Joss Whedon as an influence for a number of his heroines, so it's no surprise to see the name given to Tony's 'new girl.' The A.I. is also based on a minor one from the comics, named for the same film.
Marvel made no secret of the fact that they would be departing from the comic book origins of Ultron (specifically, removing Ant-Man Hank Pym from the equation). Even so, there is another large nod to the original Ultron, in the form of Jocasta - another program glimpsed when Tony loads up F.R.I.D.A.Y. before the final fight. In the comics, Jocasta was built as a bride for Ultron, and blessed with the 'life essence' of Wasp a.k.a. Janet van Dyne.
When Ultron is ruminating with The Twins about the irony of his creation at Stark's hands, he posits the theory that people tend to create what they most fear: Those seeking peace make machines of war, people make (little people?.... Children!) and invaders create avengers. The line is likely a subtle nod to the WWII superhero team known as The Invaders, consisting of Captain America, Bucky, Human Torch, Torch's sidekick Toro, and Namor. As comic fans know, The Invaders were the precursor of the modern Avengers.
Loyal Launch Technician
Who says acts of heroism have to be grand to be meaningful? During the HYDRA reveal in The Winter Soldier, one member of the S.H.I.E.L.D. team makes his loyalties known, refusing to launch the trio of attack ships knowing he may be executed as a result. The 'Launch Technician' (played by Aaron Himelstein) made his way into Fury's good books with the act, as he's prominently featured aboard the commandeered Helicarrier in Age of Ultron.
Vision's decision to rescue Scarlet Witch during the film's climactic battle wasn't a romantic one, but the love affair shared between the two in the pages of Marvel Comics meant that every fan saw the act as something more than simple heroism. Just how far the studio intends to take this version of the relationship remains to be seen.
The New Avengers
With Avengers Tower holding too many bad memories, and Tony Stark seemingly parting ways with the team for the moment, audiences are given a look at the "New Avengers Base" in upstate New York. The word "new" here is obviously a statement of fact, but it may also be an overt reference to Cap's New Avengers, the comic title used to distinguish the next wave of heroes from the original roster. Whether the name will stick... we'll have to wait and see.
Post-Credits Infinity Gauntlet
The Mad Titan, Thanos once again returns to be teased at The Avengers' conclusion, putting on the Infinity Gauntlet and setting out to, presumably, collect the Infinity Stones himself. The mythology behind the gauntlet and stones are still being uncovered by the film's characters, but Thor's vision is the closest to the comic book version of the weapon we have yet seen.
Those are all the easter eggs, bits of comic book trivia, and subtle references fans can look out for on repeat viewings of The Avengers: Age of Ultron, but if you have any that have been missed, please share them in the comments (we can always update.
If you’ve seen the movie and want to discuss details about the film without worrying about spoiling it for those who haven’t seen it, please head over to our Age of Ultron Spoilers Discussion.
The Avengers: Age of Ultron releases in theaters on May 1 2015, followed by Ant-Man on July 17 2015, Captain America: Civil War on May 6 2016, Doctor Strange on November 4 2016, Guardians of the Galaxy 2 on May 5 2017, Spider-Man on July 28, 2017, Thor: Ragnarok on November 3 2017, Avengers: Infinity War - Part 1 on May 4 2018, Black Panther on July 6 2018, Captain Marvel on November 2 2018, Avengers: Infinity War - Part 2 on May 3 2019 and Inhumans on July 12, 2019.