Robert Downey Jr. kept food hidden all over the lab set and apparently nobody could find where it was, so they just let him continue doing it. In the movie, that's his actual food he's offering and when he was eating, it wasn't scripted. He was just hungry.
Reputedly a scene was filmed during the final battle where Captain America saves an old man trying to protect his grandchildren. He tells him to 'Get them to cover' but as he walks away the old man asks him "Cap, is that really you?'. He turns and, noting the man's World War II veteran lapel pin, trades salutes with him. As Captain America sprints away the children ask their grandfather 'Do you know him?' and he replies 'We ALL know him'.
There were very few times that everyone was in town at once, but on one night when they were, Chris Evans sent them all a text message simply saying "Assemble" (the tagline to the movie), prompting a night out on the town. Clark Gregg has stated that this is his favorite text message that he has ever received.
After Thor takes Loki off the Quinjet down on the mountain side, two large ravens fly by them as they are talking. In Norse mythology, their father, Odin, had two ravens, Huginn and Muninn, who would bring Odin information from Midgard (Earth).
The final end credit scene was added after Robert Downey Jr. encouraged a scene rewrite: after Tony Stark falls back to Earth, he originally awakens and asks, "What's next?" Robert Downey Jr. thought the line could be more interesting, and the idea of going to a local shawarma restaurant was born. The scene was added one day after the global premiere. Since then, shawarma sales in Los Angeles, St. Louis, and Boston have reportedly skyrocketed.
According to director Joss Whedon, the original cut of the movie was over 3 hours long. About 30 minutes of the excised footage is included on the Blu-ray, most of which revolves around Steve Rogers (Captain America) struggling to adjust to the modern world. Chris Evans has since announced that these deleted scenes will be used for Captain America: The Winter Soldier (2014).
The Avengers surpassed The Dark Knight's (2008)s record of $1,001,921,825 to become the highest grossing comic book film of all time.
Thor is knocked off screen four times: twice by Iron Man and twice by Hulk.
According to Vulture, this is the amount of screen time each hero has in the film:
Captain America - 37:42.
Iron Man - 37:01.
Black Widow - 33:35.
Bruce Banner/The Hulk - 28:03.
Thor - 25:52.
Hawkeye - 12:44.