keep it civil folks.
point blank, where the hole is and where the wrist pin is at are two totally opposite ends of the engine. the rod broke off at the bottom, probably at the crank. thats what blows a hole. a wrist pin is situated horizontally through a hole at the top of the rod and thus through a hole at the base of the piston. it cannot "fall out". i cannot say this enough. a wrist pin CANNOT fall out of anything inside an assembled engine. it has no place to go, period. it cannot move up and down inside the rod and piston, because the clearances between the pin and the holes it slides into are less than a millimeter. is it a lubricated snug fit. if the clip breaks, the pin will, at worst, slide over to the side and scratch up and down on the cylinder wall. the pin is not short enough even to slide all the way to one side and drop the rod out even if a clip breaks.
only thing i could think of, the clip snapped, wrist pin slid to one side, made contact with the cylinder wall at engine speed (hundreds to thousands of rpms) and the repeated high speed impacts and vibrations traveled into the rotating assembly (pistons, rods, crank) and broke the weakest link. which would frankly be yet one more piece of evidence to deflate the "factory forged super strong rod" idiocy that lingers out here in the community.
i hate to even speculate further because it doesn't matter. one more blown engine, warranty is fixing it, customer is selling his car, community goes on, as the world turns...