The scene where Rosie and Alex are lying on Rosie's bed with baby Katie was not originally planned. The baby actress was asleep on the set and Lily Collins and Sam Claflin were on the bed with her, waiting while she rested. Director Christian Ditter decided to improvise and put it into the movie.
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 U.S. or 'Where Rainbows End' in Ireland where the author is from.
Many of the photos in Rosie's bedroom in her parents' house are Lily Collins's own photos of herself and her friends.