The final end credit scene was added after 'Robert Downey Jr'. encouraged a rewrite of a previous scene. After Thor rips off Iron Man's mask to reveal an unconscious Tony Stark, who had just fallen back to Earth, Tony 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 two days after the Hollywood premiere.
Mark Ruffalo claims to be the only actor to date (2012) to play both The Hulk and Bruce Banner in the same movie. Technically, both Eric Bana and Edward Norton have done motion capture work for their respective Hulks, but Ruffalo is the first actor to perform the Hulk live on set via performance capture.
With Samuel L. Jackson's role as Nick Fury in this film, he is now the second actor afterHugh Jackman (who has appeared in all X-men movies) to play the same comic book superhero in five different movies.
Complex legal issues prevented a number of "Avengers" characters from their inclusion in this film. Most notably, these include Quicksilver and The Scarlet Witch, the twin children of X-Men villain Magneto, and frequent adversaries Doctor Doom (nemesis of theFantastic Four) and Norman Osbourne/Green Goblin (the primary antagonist of Spider-Man). Though all characters are owned by Marvel/Disney, the "X-Men" and "Fantastic Four" characters had all been licensed to Fox Studios, and those of "Spider-Man" to Sony before work began on an "Avengers" film. Marvel has said that in the future they hope to regain the rights to all licensed properties, that the aforementioned characters might have a role in subsequent "Avengers" films.
According to director Joss Whedon, the original cut of the movie was over 3 hours long. There will be about 30 minutes of the excised footage included in the DVD Release, most of which revolves around Steve Rogers (Captain America). Whedon revealed that one of these scenes involved Rogers struggling to adjust to the modern world in his Brooklyn apartment and another revealed Steve Rogers' reunion with Peggy Carter, his love interest from Captain America: The First Avenger.
Reputedly a scene was filmed where during the final battle 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 2 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'.
The decimation of Stark Tower during the final battle destroys the company logo, leaving only the illuminated "A" at the end of the film. This is a subtle nod (and potential sequel set-up) to the comics where the Avengers operate out of a giant building alternatively depicted as an "A" shaped building, or as a skyscraper with a giant "A" crowning the top.
The character the minion is talking to in the credits is Thanos the Mad Titan, a major supervillain in the Marvel Universe. He is a cosmic mass murderer who is literally in love with the personification of Death, which is why he is smiling at the phrase, "To court with death."
Chris Hemsworth had to increase and expand his dietary/food intake in order to maintain the physique he built up for Thor.
Lou Ferrigno voices the Hulk in this film. He has played the Hulk in almost every live-action version since 1978: he played the Hulk in The Incredible Hulk and its subsequent three TV specials, and he voiced the Hulk in the big-screen The Incredible Hulk (he was seen in Hulk but it was a cameo role as a security guard, which he repeated in The Incredible Hulk ). He also has voiced the Hulk in various animated productions.
Before Mark Ruffalo was cast as The Hulk, Joaquin Phoenix was rumored for the part.