According to the Christmas 2006 issue of People magazine, Jeffrey Dean Morgan had to learn to play the guitar for his part in this film in a very short time. His guitar instructor was Nancy Wilson of the band Heart. Morgan was thrilled to take lessons from her, because, in his own words, "I had such a crush on her as a kid."
The whole letter Gerry sent to his mom and dad in Ireland says: "Dear Mum & Dad. Well, Doc says there's not much time, so I thought I'd write to you, seeing how bad we Kennedy's are with modern day contraptions like telephones. Tell Dad to not lay about, and to take care of his legs-keep them walking. I always think of Dad walking across the farm yelling after the hands too lazy to keep the chickens fed. And you Mum, yelling at Dad to treat the boys with a Father's hand, not a father's belt. I remember everything Mum. And I thank you for giving me a mother's breath of life and love. No son ever loved a mother more, I can tell you that. Never could say it to your face. Nor to Dad. But I love you."
During Holly's dream sequence (when she asks "Do all Irishmen sing?" and he answers, "Only the really well-hung ones"), Gerry is on an acoustic guitar, and singing "Love You Till The End" by The Pogues.