tested in r6684, a bug exists in which you can stand where you shouldn't be able to stand off of a ledge that is surrounded in death material. most profoundly useful in time trial in an instance like this:
as you can see above, death material extends over the top of this floating vertical platform where i've placed some laser particles. but:
it's possible to stand safely on this platform still
and as far as i can see in mid-air actually
not only that, but it isn't all that difficult to do by jumping to the platform. this death material shouldn't have to extend over the side of the geometry at all in order to kill the protagonist. i think it has to do with what part of the player death material must touch in order to have an effect on the player, and how that must be adjusted in order for more accurate scenarios and less abuse.
if it helps i've also experienced more than one time where the player can effectively parkour through a solid wall of death material the same width of that platform and remain alive inexplicably. it's very hard to reproduce and i don't have it recorded.