Gunshot squibs are little micro-explosive devices that leak or spray dark-red glop to indicate that a character has been shot. They’re been used by filmmakers for the last half-century or so. The first time I noticed them was during the machine-gun slaughter scene at the end of Bonnie and Clyde. Since the early ’80s I’ve been on dozens of film sets and talked to two or three guys who knew all about squibbing, but I never once heard about squibs being activated by crew guys pulling on fly-fishing lines. These were apparently used in the gangland massacre of Sonny Corleone scene in The Godfather. It seems kind of silly to yank on two or three fishing lines in order to make a bullet hole or two appear. With the sound of rattling gunfire and the screaming and abundant bleeding and the fast cutting who’s going to notice if a little black hole or two suddenly appears on James Caan‘s face? Nobody.