1. Cillian Murphy auditioned for the role of Batman in Batman Begins, but they thought he'd be better suited to Scarecrow.
2. Christian Bale auditioned with the now-famous growly Batman voice, and wasn't sure how well it would go down. When he showed his wife the voice he used, she said, "Well, you fucked that one up, didn't you?"
3. Darren Aronofsky was set to direct a Batman movie based on the comic book Year One, but his original pitch involved an older Batman played by Clint Eastwood.
4. According to his Deadpool costar Morena Baccarin, it took seven hours to do Ryan Reynolds's face and body makeup.
5. Ryan Reynolds has said there’s over 100 easter eggs, cameos, and pop culture references in Deadpool.
6. Michael B. Jordan kept to himself on the set of Black Panther to reflect how his character would feel lonely and isolated.
7. The Black Panther necklace T'Challa wears looks super heavy, but it's actually made of light rubber.
8. Gal Gadot was five months pregnant during reshoots of Wonder Woman so they cut a hole in her costume and put green cloth over her stomach, essentially turning it into a green screen.
9. Joss Whedon almost made a Wonder Woman movie years ago, and Cobie Smulders was a potential lead. She later went on to voice the character in The Lego Movie.
10. Margot Robbie did almost all of her own stunts for Suicide Squad, including an elevator fight scene where she literally runs up a wall without even wearing a harness.
11. The “he’s a friend from work” line in Thor: Ragnarok was thought of by a Make-A-Wish child visiting the set.
12. Thor: Ragnarok was also the first time that Mark Ruffalo voiced the Hulk. Previously the character has been voiced in MCU films by Lou Ferrigno.
13. The movie was originally going to feature Odin living on the streets of New York before dying, but test audiences didn't respond well to it.
14. The CEO of Warner Brothers reportedly ordered that Justice League should be under two hours long, after backlash about the running times of other DCEU films.
15. There were initially scenes in Justice League featuring Victor's life before he became Cyborg, but they were all cut.
16. Patrick Stewart lost 20 pounds for his role as Charles Xavier in Logan, in order to make him look older and frailer.
17. Hugh Jackman has kept a Wolverine suit and claws from every movie he’s done and then sells them to raise money for charity.
18. During his time playing Wolverine, Hugh Jackman would take freezing cold showers in the morning, as it would piss him off and get himself into the angry mood of the character.
19. Due to character rights issues between Marvel Studios and 20th Century Fox, Quicksilver had a different origin story in Avengers: Age of Ultron and is never referred to as a mutant. Nor is his sister, Scarlet Witch.
20. Tom Hardy had to wear shoes with a three-inch lift in them while filming The Dark Knight Rises so that he could stand eye-to-eye with his costars.
21. There's a reason the the Joker is never mentioned in The Dark Knight Rises – Christopher Nolan has said, "I didn’t want to in any way try and account for a real-life tragedy. That seemed inappropriate to me."
22. When Jack Nicholson initially turned down the role of the Joker in Batman it was offered to Robin Williams.
23. Amy Adams auditioned for the role of Lois Lane on two separate occasions before landing the role in Man of Steel.
24. Henry Cavill only has 43 lines in the whole of Batman v Superman: Dawn of Justice (42 if you exclude his scream).
25. Leonardo DiCaprio was in talks to be Spider-Man back when James Cameron was said to be developing a movie. Leo has since said the talks never went very far but that there was a screenplay.
26. Shailene Woodley was cast as Mary Jane Watson in The Amazing Spider-Man 2 and even filmed scenes, but was cut to streamline the film.
27. For Spider-Man: Homecoming, they didn't want to show things that audiences had already seen in previous Spider-Man movies, which is why there's no Harry Osborn or mention of the Daily Bugle.
28. Tom Holland wasn't allowed to play with the spider webbing during Spider-Man: Homecoming as he dropped a container of it on the first day and smashed it everywhere.
29. He also wasn't allowed to read the whole script for Avengers: Infinity War in case he gave away spoilers.
30. During filming for Guardians of the Galaxy Vol. 2, Dave Bautista would have to go into a sauna to melt off his Drax makeup, as scrubbing it was too abrasive. He even had his own portable sauna.
31. Michelle Pfeiffer had to be vacuum sealed into her Catwoman costume during Batman Returns.
32. Working with real-life penguins for Batman Returns means the set had to be much colder than any human would be comfortable with. The penguins also had their own area of the studio, complete with a swimming pool and refrigerated dressing rooms.
CORRECTION
Shailene Woodley's name was misspelled in an earlier version of this post.