The titles for each episode are an onomatopoeia alluding to the method of murder used by the killer in that particular episode.
After the pilot presentation was greenlit to series, several roles were recast:
-Ryan Merriman (Henry Dunn) was replaced by Christopher Gorham.
-Samantha Noble (Trish Wellington) was replaced by Katie Cassidy.
-Bill Dow (Sheriff Mills) was replaced by Jim Beaver.
-Gerard Plunkett (Thomas Wellington) was replaced by Richard Burgi.
-Bill Pullman (Uncle Marty) was replaced by Harry Hamlin.
-Ryan Merriman (Henry Dunn) was replaced by Christopher Gorham.
-Samantha Noble (Trish Wellington) was replaced by Katie Cassidy.
-Bill Dow (Sheriff Mills) was replaced by Jim Beaver.
-Gerard Plunkett (Thomas Wellington) was replaced by Richard Burgi.
-Bill Pullman (Uncle Marty) was replaced by Harry Hamlin.
Co-executive producer Dan Shotz stated that finding someone for the role of Abby Mills was the most difficult part of casting, with hundreds of actresses auditioning. Elaine Cassidy was found after her self made audition tape was sent from London to Los Angeles, four days before filming on the pilot presentation began.
All TV ads and previews for Harper's Island indicated that it would be only a 13-episode series, meaning only one season of the show, with the mystery antagonist revealed in the final episode.
Katie Cassidy, Gina Holden, Callum Keith Rennie, Jim Beaver, Amber Borycki, Chris Gauthier, Ben Cotton, Sean Rogerson, Dean Wray, Jay Brazeau, Aaron Pearl,Alex Ferris, Maxine Miller, Anna Mae Routledge, Sarah-Jane Redmond, and Sarah Smyth have all appeared in episodes of Sobrenatural (2005), though not at the same time with the exception of Gina Holden and Callum Keith Rennie who were both in "Wendigo." Also Jim Beaver and Katie Cassidy were in a few episodes together.