I've discovered a few items that allow players to not only get out of bounds, but skip entire levels.
Ender Pearl:
Players can use enderpearls to phase through one block thick walls/doors, (so nearly every single door and wall) allowing players to skip every level without having to have an encounter of enemies, nor obtain any weapons.
This is done simply by throwing an enderpearl on the furthest edge of a block that is touching a wall (so either a roof or floor, to glitch upwards or downwards), this will phase you into the wall, and jumping or walking gets you through the wall/door, or ceiling to be out of bounds (though to phase through a door you need to be sprinting (and not constantly firing enderpearls)).
Chorus Fruit:
This one is obvious, it teleports you randomly. This can cause players to get "soft-locked" (you can still exit the level or use enderpearls). But, it also allows players to get to w.i.p. areas (1-2's secret exit under the entrance as an example), and also through doors (occasionally).
Fire Charges:
Surprisingly, unlike flint and steel, this item can still be used everywhere (in any room, any protected area, good luck removing the flames though).
It can burn down the doors of Limbo (as they are all spruce planks).
You do not need skulls to beat Limbo (again).
I've discovered a few items that allow players to not only get out of bounds, but skip entire levels.
Ender Pearl: Players can use enderpearls to phase through one block thick walls/doors, (so nearly every single door and wall) allowing players to skip every level without having to have an encounter of enemies, nor obtain any weapons. This is done simply by throwing an enderpearl on the furthest edge of a block that is touching a wall (so either a roof or floor, to glitch upwards or downwards), this will phase you into the wall, and jumping or walking gets you through the wall/door, or ceiling to be out of bounds (though to phase through a door you need to be sprinting (and not constantly firing enderpearls)).
Chorus Fruit: This one is obvious, it teleports you randomly. This can cause players to get "soft-locked" (you can still exit the level or use enderpearls). But, it also allows players to get to w.i.p. areas (1-2's secret exit under the entrance as an example), and also through doors (occasionally).
Fire Charges: Surprisingly, unlike flint and steel, this item can still be used everywhere (in any room, any protected area, good luck removing the flames though). It can burn down the doors of Limbo (as they are all spruce planks). You do not need skulls to beat Limbo (again).
Here is a video (no talking, and not that detailed) showcasing the bugs: https://www.youtube.com/watch?v=zurwQOvsEKs&ab_channel=BananaTom