Unlike the novel, the film is set over 12 years instead of 45 years
Based on a book by Cecelia Ahern originally called "Rosie Dunne" in the US and "Where Rainbows End" in Ireland, the author's birthplace.
Many of the photos in Rosie's bedroom in her parents' house are Lily Collins's own photos of herself and her friends.
Director Christian Ditter allowed Lily Collins and Sam Claflin to improvise the scene where Rosie and Alex walk the streets of Boston after their night out. Both actors said that this was their favorite moment of the shoot.
It was filmed in Dublin, Ireland.