Ya' gotta' love it when your horse goes over the side of a small ledge and somehow lands on his feet and keeps going like nothing ever happened in Red Dead Redemption..
I'm not sure if it's a glitch or not because of the "Dastardly" achievement on the XBox 360 version, but in
Red Dead Redemption, if you kidnap a whore in town and hogtie her and bring her out into the country on horseback, then dump her hogtied body on the railroad tracks to get run over and squished by an oncoming train (the achievement is a measly 5 points, bummer), before the train strikes her prone body your horse will jump on to the tracks and commit Mr. Ed suicide via playing chicken with the train!
I've tried different methods like ditching the horse away from the tracks before I kill my whore, but the horse will even run from afar and kill himself with the train. I've even tried shooting my horse to scare him off (I would have made a great cowboy) but to no avail. I dunno, I'm still stoked that gruesomely killing a prostitute via a speeding locomotive is rewarded by the game. Rockstar are some wonderfully sick individuals!