1. For a while, the movie's directors wanted Jennifer Garner and Mark Ruffalo to play the young versions of themselves.
2. But they eventually cast Christa B. Allen as the young version of Jenna, Jennifer Garner's character. At the time, Garner said that Allen looked identical to her as a teenager.
3. When a 12-year-old Allen asked Garner for advice on breaking into the industry, Garner told her, "Make sure that you maintain a life outside of Hollywood because if you're just wrapped up in your career all of the time, you're not a real person having real experiences. And then how can you play a real person in a movie?"
4. Allen said that the most awkward scene to film was the one where she had to stuff her bra with toilet paper.
5. Years later, Allen played another young version of one of Garner's characters in Ghosts of Girlfriends Past.
6. She also went on to play Charlotte Clarke in Revenge.
7. Sean Marquette, who played a young version of Mark Ruffalo's character, Matt, wore a fat suit for filming.
8. And he was told to be "more awkward" because the director thought he was too cool.
9. Allen, on the other hand, was considered just the right amount of awkward for the role, and was cast even though she had never acted before.
10. Judy Greer, who plays Lucy (Tom-Tom), said that she was a much uglier teenager than Alexandra Kyle, who played the young version of her character.
11. But Greer's mother thought their resemblance was so uncanny that when she met Kyle she said, "Oh, this is just like seeing my daughter again!"
12. Before Jennifer Garner was cast, Renée Zellweger was considered for the role of Jenna.
13. Eventually, Garner was cast before Ruffalo. But she said she was thrilled when she heard he was being considered since she was such a big fan of his.
14. And it was Garner who suggested that Gary Winick should direct the movie.
15. Garner and Greer are friends IRL.
16. The Six Chicks included Ashley Benson, who went on to appear in Pretty Little Liars, and Brie Larson, who is in Room.
17. The movie's costume designers purposely dressed Jenna in pretty pink clothing to make her appear younger. They also dressed Lucy in harsh colours to emphasise that she was an adult.
18. Filming in New York City was difficult because the paparazzi kept hounding Garner.
19. The movie has a deleted scene in which adult Jenna goes to the doctor, and the doctor compliments her on her tattoo. As soon as the doctor leaves the room, she checks her whole body for it.
20. Jenna turns 30 exactly 13 minutes into the movie.
21. The blindfold that 13-year-old Jenna wears is made of the same material as the eye cover she wears when she wakes up as a 30-year-old.
22. And the picture of Madonna that is on the table of 13-year-old Jenna's room reappears when Jenna is 30. This time, though, it is signed.
23. Similarly, the Poise article that Jenna reads at 13 features the flat that she ends up living in at 30.
24. The dollhouse that Matt gives Jenna for her birthday is the same colour as the house they end up in at the end of the movie.
25. Lots of the scenes between Garner and Ruffalo were improvised.
26. And although Ruffalo was nervous about filming the "Thriller" dance scene, he says Garner had a musical theatre background and coached him through it.
27. When Jenna speaks to Matt before his wedding, Time's Arrow is on the bookshelf behind him. It's a book about a man who experiences life in reverse.
28. And finally, it's kinda weird that Jennifer Lopez, who was dating Ben Affleck at the time of filming, is on the cover of Sparkle in the movie when Jennifer Garner would go on to have a family with him.