The tracking shots in the grocery store were created by putting the camera operator into a shopping cart.
Other than a cameo from Leslie Wimmer Osborne, the only cast member to return from Paul Osborne's previous film FAVOR is Patrick Day. Day's character in CRUEL HEARTS is specifically written to be the opposite of his FAVOR character - successful vs unsuccessful, wealthy vs poor, fit vs fat, married vs single, smart vs clueless, in control vs out of control, groomed vs un-groomed, accustomed to violence vs driven mad by violence.
Australian filmmaker Russell Southam designed and created all the incredibly realistic fake government IDs for the movie and then had to figure out how to ship them internationally to the production without causing a forgery incident with Interpol or customs.
Producer Jonathan Brown personally designed two different rigs to achieve the upside-down shot. The other shots where the perspective goes from upside-down to right-side up were done by duct-taping the camera to the wheel of a moving dolly.
Alev Aydin's character's name is never revealed. In the script he's introduced as a "Young Guy"; he identifies himself twice in the film as "I'm nobody, I'm just some guy"; the graphic at the top of his chapter in the movie calls him "The Stranger"; and in the end credits he's listed again as "Just Some Guy".