1. you can get caught by sand coffin while you are already in a sand coffin. havent tried if u can get burial'ed by all the coffin users.
2. when you die with a bleeding effect on, you respawn and rest right away while ur hp is 0 you die. This effect can be repeated 3 times. (only tried this with coffin and spear passive, dont know if this is applied to burning for uchihas or other bleeds)
3. Flamboyant blade of daisies makes you get negative HP
4. Dont know why but in some cases when ppl gets killed, they respawn invisible. only way to fix it is relogging