*stomach lurching* Having worked at a Wendy's as my first "job" and actually helping prepare this chili, at least I can say that you can't really blame the cook, ready for some trade secrets?
The hamburger comes from the grills, it's meat that was "staged" but didn't get into a burger because it had been on the grill for too long, so they throw it in a pan of water on the back of the grill, several times throughout the day that "chili-meat" is weighed, bagged, and frozen for use in the chill mix later. The frozen vegetables are cut to about 1/8 inch square and are in clear plastic bags that are only about 8 inches on a side, so a foreign object in there would be pretty easy to spot as well.
This leaves you with the chili base and the beans, both of which come in industrial sized tins cans, a little larger than your big coffee can, both are sealed at the factories where they are packaged, but that still leaves the picking for the beans and the processing for the chili base where someone could have very likely ended up short a finger and like Mal said, if they're an illegal they're not going to want to get deported. Also if it was a 3rd world factory they may have chosen not to report for fear of losing their job, or they did report it but the foreman chose to ignore it rather than destroy the amount of product necessary to ensure that the finger had been filtered out. Last option, the DID destroy what they though to be the tainted product but missed a bit!
All that aside, all I would really comment on is DAMN I'M GLAD IT WASN'T ME THAT FOUND IT!!!!!