First, the parakoopa glitch: This only happened to me once, but when I tried to stomp a parakoopa at about 17:14 in this video, Mario just simply fell through it and died. I think it's because I was falling too fast into it at the same time as it was rising too fast, but I don't think that would ever happen in the original games, due to the way their stomping mechanics work (as long as you're descending in midair, you'll stomp the enemy, regardless of how you collide). Next, the Bowser glitch: At about 21 minutes into that same video, after I lure a couple Bloopers to the left, the fake Bowser on the ledge under the row of ? blocks walks off of the right edge of the ledge. In the original game, he stops moving to the right a few tiles away from the edge (and he would never fall even if he did walk off the ledge because of how he's programmed).