This one was quite obscure and odd bug I discovered on survival mode.
If you pause the game and click the "Achievements" and "Statistics" buttons repeatedly. The game briefly unpauses for a moment before pausing again during the click.

Steps to reproduce:
1)Fly(or jump) off a high enough place for the fall to kill you.
2)Right before hitting the ground, pause the game.
3)Repeatedly Open the statistics and achievements menus over and over again.

If done enough times, the player dies, even though it was supposedly paused.

Obviously effects singleplayer only.