A justified example with Rose McIver who is six years older than Saoirse Ronan, despite playing her younger sister. This is because Susie remains fourteen throughout the film, whereas Lindsey ages over a few years, and the majority of her scenes take place when she's in her late teens. So casting an older actress is necessary.
Reece Ritchie was twenty-three playing Ray and Carolyn Dando was twenty-one as Ruth. AJ Michalka was conversely only seventeen as Clarissa.
Dyeing for Your Art: Stanley Tucci had his skin lightened as well as chest and arm hair dyed to match the wig he would wear. When Ryan Gosling was still attached, he gained twenty pounds of weight and grew a beard to play Jack.
The Other Marty: Ryan Gosling was cast as Jack Salmon, but he backed out right before filming started - feeling he was too young for the part.
Playing Against Type: Stanley Tucci goes radically against type here. Mostly known for comedies where he plays uptight or slightly quirky characters - here he's a rapist and child murderer.
Playing Gertrude: Almost was the case, with twenty-six year old Ryan Gosling cast as Jack Salmon initially. This would have made him only eight years older than the actress playing his middle daughter.
Reality Subtext: Alice Sebold, the author of the novel, is a survivor of rape.
So My Kids Can Watch: Peter Jackson made a surprisingly tame movie that cuts out the darkest parts of the novel.
Originally, Lynne Ramsay was going to direct the film, and had written a script in which all the scenes in heaven with Susie were depicted as being in her father's imagination, while he and Mr. Harvey became close friends.
Abigail Salmon's original plot from the books - where she has an affair with the detective - was filmed but ultimately cut from the story. This explains the chemistry between them in the scene at the police station.
Early in production, Hugh Jackman was offered the role of Jack Salmon - reuniting him with Rachel Weisz since The Fountain. He had to turn it down due to a scheduling conflict.