This is the third collaboration between Cillian Murphy (Dad) and Ken Watanabe (Kensuke). They previously starred together in Batman Begins (2005), as Dr. Jonathan Crane / Scarecrow and Ra's al Ghul, and Inception (2010), as Robert Michael Fischer and Mr. Saito. Both films were directed by Christopher Nolan.
Ken Watanabe and Sally Hawkins collaborate for the third time after starring together in Godzilla (2014) and Godzilla: King of the Monsters of the Monsterverse.
One of the most notable differences between the book and the film is that, in the novel, Micheal and Kensuke have a much greater deal of interactions with each other. In the film, their conversations are very minimal. This may have been done for the convenience of letting the visual medium of film tell the story.