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In this movie, Theo and Julian's son Dylan died from a disease epidemic, while in the book, Julian's character was the one that is pregnant, and the one Theo is protecting. In the book, Theo is married, and divorced Helen, and had a daughter named Natalie, who was killed when Theo backed out of the driveway and accidentally ran her over. This movie and the book show this death as the reason for either relationship not working. The movie changed and combined Julian and Helena, while creating Kee.
In the movie, the infertility crisis is the result of all women being infertile. In the original novel by P.D. James, it's the result of all men producing no sperm.
Writer and director Alfonso Cuarón stated that he "didn't want to make a film that ends when the credits roll. He wanted to make a film that, when the final credits roll...that's really the beginning of the film."
Sir Michael Caine plays an award-winning political cartoonist. In his house, you can see some of his cartoons in the background. They were drawn by Steve Bell, an award-winning political cartoonist for The Guardian newspaper.
Writer and director Alfonso Cuarón said in one interview that he wanted to shoot this movie like The Battle of Algiers (1966), rather than Blade Runner (1982), almost like a documentary about something that happened back in 2027.
The statue of David seen in the Ark of Arts is an existing movie prop, and it was filmed intact; however, during production, an Italian article was written about the loss of Italian cultural heritage, showing the statue with a missing leg. The idea stuck, and a part of the statue's left leg was therefore digitally removed in post-production.