In one of the Mass Effect missions, I somehow went over a rail and fell down to a lower level. For a second the screen paused, then it spawned me on the ground of the lower level.
In the same game, once I got pushed out of a level some how. A cut scene ended, then I got pushed through the wall behind me and left the level far behind as my character kept going backward.
On Darkest of Days, there's one point near the beginning of the game where you're standing still in a field firing at Confederate soldiers. On two occasions, when I got the command to move, I randomly shot up 300 feet. Both times this happened, I died. It wasn't from falling damage, it was from the Confederate soldiers having perfect aim. Hitting the ground didn't even hurt me.