The Russo brothers'quarantine watch party marked the movie's one-year anniversary with a deluge of behind-the-scenes gifts. From never-before-seen footage to development details, the night didn't disappoint.
Without further ado, let's move faster than old Captain America throwing a baseball and dive into the best of the night's tidbits.
1. Brie Larson's first day couldn't be more special
One of the best things to come out of the Russo brothers' back pocket: footage of Brie Larson greeting fellow superhero Scarlett Johansson, aka , on her first day as Captain Marvel, dressed in full Captain Marvel garb.
"This was @brielarson's first day ever as Captain Marvel… And here's a quick video of her greeting the cast for the first time," tweeted Monday during the watch party.
Larson filmed her Endgame scenes before, meaning she had the unique task of playing the fleshed-out version of the superhero before she'd experienced her formative origin story.
2. Chris Evans knew wielding Mjolnir would be epic
The Russos used one word to describe Chris Evans' reaction to learning that Cap would wield Thor's hammer, aka the scene that blew the roofs off everyone's heads.
"It was early in development when we let him know he was going to pick up the hammer… needless to say he was psyched."
3. Captain America could have embodied the soul stone
At one point, the Russos floated the idea to make Cap the soul stone. "Early on in development talks we considered making Cap the soul stone... But that idea fell away rather quickly."
Replacing the soul stone with Captain America would probably have meant we'd have had to watch Cap sacrifice himself to defeat Thanos. His loss, along with Iron Man's, might be too much to handle for some, although there are those who expected more heroes to bite the dust in the saga-ender anyway.
4. Shooting the Winter Soldier elevator scene was much easier second time round
The version of the "Hail Hydra" elevator scene in Endgame went much more smoothly the second time round for Captain America -- and the Russos. In the first Avengers, which takes place in 2012, Cap loses the mind stone hidden inside Loki's sceptre to Hydra operatives posing as SHIELD agents.
In Endgame, Cap travels back in time to that same moment, but now he knows the SHIELD agents aren't to be trusted because of what happened in 2014's The Winter Soldier. He tricks them into thinking he too hails Hydra and struts off with the stone.
When it came to filming, "We shot the original Winter Soldier elevator scene in four days," the Russos explained. Of the Endgame scene, they said, "This scene took about three hours… talking is easier to shoot than fighting..."
5. The original Hulk and Smart Hulk are one
We don't see the process by which Bruce Banner's Hulk takes the fixed state of the Smart Hulk we see in Endgame. "Does the original Hulk personality still live within Smart Hulk or is he gone now?" @joshtwitch asked the Russos.
Clarifying what happened to the mean green machine we once knew, the Russos answered, "The personality that now exists is a new entity… it is a merger of Bruce Banner and the Hulk."
6. Old Captain America's antics are a spectacle to behold off-camera
The Russo brothers have clearly been saving up their own personal collection of behind-the-scenes clips for a rainy day.
One of the best of the bunch involves Chris Evans messing around in Old Captain America's garb -- a unique look of the athletic elderly.
7. Robert Downey Jr.'s last scene was 'I am Iron Man'
While we knew the scene in which Iron Man snaps his fingers and defeats Thanos was Downey Jr.'s final scene, here we get a look at the second time that scene was shot.
Initially, Iron Man didn't say anything when he dusted off Thanos, but after editor Jeff Ford suggested the genius line to bring Iron Man full circle, the cast and crew got back together to shoot the scene again, with the added line.
The Russos imply their footage of Downey Jr.'s last day on set is that day he reshot his final scene.
More from the watch party
The Russos unloaded a swathe of behind-the-scenes photos of the cast and tidbits on filming.
Here's one of those sweet cast photos.
And here's a clip of Evans' final day of shooting, where he had to say goodbye for good to Cap after a decade of defining "America's Ass."
In this much lighter clip, Downey Jr. gives his carefully deliberated assessment of a scene featuring him and Chris Evans: "Naaailed it!" he says before they wrap shooting in New York.
"Here we are getting ready to shoot an Asgard scene at the stately cathedral in Durham. We had to wait for the choir rehearsal to finish…" the Russos tweeted.
"Here's some BTS from Joe's iPhone, walking through and planning out some of the shots for Hawkeye's time travel journey."
Here we have an unrecognizable Downtown Atlanta posing as Tokyo for filming.
Those kids who ask for the Hulk's autograph are really family members of the Russos (a cute but already known Easter egg).
Correction, 11:30 p.m. PT: This article originally misstated which stone Captain America traveled back in time for. It was the mind stone.