Java Edition:Block Replacement Bypass
From Alpha v1.0.5-1 to Beta 1.4_01, water, lava, fire, or snow could be replaced with certain blocks to create invalid states the blocks could not normally exist in. Due to the replacement of the block bypassing the initial update check, the blocks are able to be placed.
Uses
Brown Mushroom
Brown mushrooms can be placed invalidly using this method from Alpha v1.0.5 to Beta 1.4_01 but they will only last temporarily until they receive an update. This will then cause them to break off, making it a temporary discontinued feature.
Water that was just placed for BRB
The water replaced with a brown mushroom, leaving it floating
Cactus
Cactus could be placed on invalid and floating positions from Alpha v1.0.5 to Beta 1.4_01. As long as the cactus does not receive growth updates, such as with a block on top of the cactus, it will remain in that state forever.
Water that was just placed for BRB
The water replaced with a cactus, leaving it floating and next to a solid block
Cake
Cake can be placed invalidly from Beta 1.2 (introduction of cake) to Beta 1.4_01 using this method. Cakes placed in this state can be eaten without making the block break or disappear.
Water that was just placed for BRB
The water replaced with a cake, leaving it floating
Chest
Chests can be placed next to chests you otherwise couldn't, creating triple, quadruple, or even quintuple chests.
Dandelion
Dandelions can be placed invalidly using this method from Alpha v1.0.5 to Beta 1.4_01 but they will only last temporarily until they receive an update. This will then cause them to break off, making it a temporary discontinued feature.
Water that was just placed for BRB
The water replaced with a dandelion, leaving it floating
Rose
Roses can be placed invalidly using this method from Alpha v1.0.5 to Beta 1.4_01 but they will only last temporarily until they receive an update. This will then cause them to break off, making it a temporary discontinued feature.
Water that was just placed for BRB
The water replaced with a rose, leaving it floating
Ladder
Ladders can be placed invalidly using this method from Alpha v1.0.5 to Beta 1.4_01. This can be used to put ladders on transparent blocks and even air. Placing the ladder on air will cause it to render as invisible with only the hitbox being visible. The hitbox will change orientation to match the hitbox of the last ladder the player has looked directly at, and if no valid ladder has previously existed in the world, it will be a full block.
Lever
Levers are perhaps the most interesting on this list because they are the exception. Placing a lever using this method on the top side of a block creates levers with data values [test].
Rail
Rails can be placed in many invalid states using this bug, from floating rails of any kind to rails on top of rails. It should be noted that a floating rail will drop if it receives a block update. However you can place and ride minecarts on them.
Water that was just placed for BRB
The water replaced with a rail, leaving it floating
Red Mushroom
Red mushrooms can be placed invalidly using this method from Alpha v1.0.5 to Beta 1.4_01 but they will only last temporarily until they receive an update. This will then cause them to break off, making it a temporary discontinued feature.
Water that was just placed for BRB
The water replaced with a red mushroom, leaving it floating
Saplings
Saplings can be placed invalidly using this method from Alpha v1.0.5 to Beta 1.4_01 but they will only last temporarily until they receive an update. This will then cause them to break off, making it a temporary discontinued feature.
Water that was just placed for BRB
The water replaced with a sapling, leaving it floating
Stone Button
Stone buttons can be placed from Alpha v1.0.5 to Beta 1.4_01 using this method. It will remain in this invalid state until it is activated, then it will update and break off, making it a temporary discontinued feature.
Water that was just placed for BRB
The water replaced with a stone button, leaving it floating
Stone Pressure Plate
Stone Pressure Plates can be placed from Alpha v1.0.5 to Beta 1.4_01 using this method. It will remain in this invalid state until it is activated, then it will update and break off, making it a temporary discontinued feature.
Water that was just placed for BRB
The water replaced with a stone pressure plate, leaving it floating
Sugar Cane
Sugar cane could be placed on invalid and floating positions from Alpha v1.0.5 to Beta 1.4_01. As long as the sugar cane does not receive growth updates, such as with a block on top of it, making it a permanent discontinued feature.
Water that was just placed for BRB
The water replaced with a sugar cane, leaving it floating
Wooden Pressure Plate
Wooden Pressure Plates can be placed from Alpha v1.0.5 to Beta 1.4_01 using this method. It will remain in this invalid state until it is activated, then it will update and break off, making it a temporary discontinued feature.
Water that was just placed for BRB
The water replaced with a wooden pressure plate, leaving it floating
