In August 2010, Scott Caan injured his knee while filming a stunt for the show and tore an ACL. The injury was written into the show.
The HPD police cruisers used throughout the series are the civilian-spec Chevrolet Impala sedans (2006 - 2013 including the 2014-16 Impala Limited) seen with the HPD livery. The Impala squads seen throughout the series have the 5-spoke alloy wheels - which is not available with the 9C1 police package option (2006 - present Impalas come with 16 inch steel wheels with bolt-on center caps or the full-wheel hubcaps seen on the civilian 2000-05 base Impala - 2012-16 models came with 17 inch steel wheels). Commencing in Season 7 this also applies to the civilian-spec 2007-14 Chevrolet Tahoe and 2011-17 Caprice PPV (while the newer models are not sold to the general public the 2011 model or those with over 100,000 miles are being are being seen during Season 7).
Each episode title is in the Hawaiian language.