The waterfront shown prominently is the Cape Fear River at Southport, North Carolina. The lighthouse seen several times across the river is the Oak Island Lighthouse.
Lead star Josh Duhamel invited some local Southport, North Carolina restaurant staffers to go sailing with him during filming.
In the book, it goes into much more detail of Kevin's abusive behavior as well as Katie's character being less trusting. Alex is a retired military police officer and recognized Katie's behavior of being abused and helps her through it.
This is the 8th film adapted from a Nicholas Sparks novel and the second one to be directed by Lasse Hallström, the first one being Dear John (2010).