These features were once in MCPE, but were removed.
List of Removed Features
Cyan Flowers were coded in the game as replacements for the Rose. They were removed in Update 0.9.0 when they were replaced by Poppies.
Cameras were added as a means to take screenshots in-game. They were only accessible through inventory editing and were removed in Update 0.9.0.
It was stated it may be re-added with a proper image sharing system.
Gravel Blocks were used as paths on Villages, but in the Update 0.11.0, it is replaced by Grass Paths (pressed dirt) created by using a Shovel on Grass.
In 0.9.0, a glitch caused edges of the worlds spawned with hydrated Farmland. This was removed in a future 0.9.0 update.
The Reactor was replaced by the Nether dimension in 0.12.1.
The Stonecutter was removed from Survival Mode in Update 0.13.0, and its functions were moved to the Crafting Table. It can still be found in the Creative mode inventory.