Jack (get it? One-eyed Jack?!) was owned by American pilot and soldier of fortune Jake Cutter (Stephen Collins) who resided on the South Pacific island of Bora Gora during the days before World War II. At one time, Jack had a glass eye (an opal with a sapphire center) but Jake Cutter lost it on a gambling wager.

Jack the dog was played by Leo the dog (who had both his eyes). To communicate with his owner, Leo used a simple barking system. One bark meant "No"; and two barks meant "Yes."

According to trainer Karl Lewis Miller, when the patch was placed over Leo's eye, his one ear would stand up as if trying to compensate with sound waves for the lose of vision in the one eye. "He didn't wear that patch all the time, just when they rolled the camera, said Miller, "but every time, we put that patch on to work him, you could tell he was constantly trying to figure out what was going on on that side, and that ear started working like radar."

Leo's breed is a mix between a Staffordshire Bull Terrier and a Smooth Fox Terrier. Born in 1968, Leo passed away at age 21 on April 6, 1989. The Oklahoma Film Society owns pictures and a history of the dog.

Leo's acting credits included the movie Shampoo starring Warren Beatty and the TV cop drama THE BLUE KNIGHT starring George Kennedy (as a stray dog who tagged along with Bumper Morgan, a cop who walked a beat in Los Angeles). He also did work on the military comedy M*A*S*H, the sitcom PUNKY BREWSTER and the western drama KUNG FU.