Avengers age of Ultron has been out for a while now but it still is worth talking about.
1. The scene that shows Black Widow with the Russian gangsters as she speaks over the phone was written by Joss Whedon 10 years before he the script for The Avengers was completed.
2. Robert Downey Jr. would often hide snacks on the set of The Avengers.
3. Olympic archers trained Jeremy Renner before The Avengers was shot so he could prepare for his role as Hawkeye.
4. The Avengers is the first ever Marvel Studios movie to make over $1 billion worldwide.
5. Thor, played by Chris Hemsworth, is knocked off screen in total four times during the movie. Twice by Iron Man and twice by the Hulk.
6. In the United Kingdom, the movie is titled Marvel: Avengers Assemble as Disney were worried about confusion with the famous British espionage franchise also called The Avengers.
7. The Avengers is the highest grossing movie ever... not to be directed by James Cameron!
8. Joss Whedon wanted Marvel's 'The Wasp' to be in the movie. In fact, she even appeared in early drafts of the script before being cut.
9. The Avengers is the first film to gross a massive $200 million in its first three days after opening in the US!!!
10. The title screen doesn't appear in the movie until 12 minutes into the film!
I got all of the facts from the following links: