In the movie, Maddy's mother says Olly needs a haircut. In the book, Olly has a shaved head.

Olly's life at home was a bigger role in the book than in the movie. The book goes more into depth on Olly's life and his person.

There is a scene in the movie where the astronaut is sitting on a bar stool in a diner that Maddy created. This scene is a reference to the famous 1942 painting "Nighthawks" by American artist Edward Hopper.

When Olly and Maddy first exchange phone numbers, we can see that the last four digits of his number read 0117, which look like a numerical spelling of "Olly."

The watch Olly wears is a Casio F-91w and is now owned by a fan in New York.

This movie is based on the book Everything Everything by Nicola Yoon.

In the book they only IM and email whereas in the movie they text message.

In the movie, Olly has brown colored eyes. In the book, Olly is written to have ocean blue colored eyes and an olive complexion.

Is based on the 2015 young-adult novel of the same name by Nicola Yoon.

There are minor differences between the book and the movie. In the book, when Olly visits Maddy, he does all of these parkour tricks and teaches Maddy to do a handstand. In the movie, she claims she can do a handstand right away and does one. The movie heavily emphasizes Carla's daughter, Rosa's, role in the story. In the book, when Olly and Maddy get to Hawaii, he has to convince a native Hawaiian lady to giver Maddy a lei. In the book, Maddy's suit is bright pink, not yellow. In the book, they meet with Olly's gay rockstar friend at a restaurant.

The email Maddy opens from Olly about Olly leaving, has slightly different content than what can be heard in the voiceover.