Tom McCarthy wrote the three main roles directly for the actors who ended up playing them. McCarthy has stated in interviews that at the time of writing he was friends with Peter Dinklage, an acquaintance and a colleague of Bobby Cannavale and almost a complete stranger to Patricia Clarkson.
The train depot seen in the film still remains in Newfoundland, NJ. It is a popular spot for railfans to take pictures of the Susquahanna trains as they chase them north through NJ, just as Joe and Fin did in the film.
Perhaps it is not coincidental Finbar McBride's namesake or patron is St. Finbar (550-620), who lived as a religious hermit. Despite choosing a remote place to found a monastery, Finbar attracted many, even as many as to eventually increase into the city of Cork. The similarities are striking between the character and the bishop.