Iron Door

Iron doors are in the game code, but they are not used. Using MCPE Edit software you can get the Iron Door. Because there is no redstone there is no way out. This would make a good trap. The bottom is glitched out and looks like a broken glass pane.

Trivia

 * Appears See Through unless you use a texture pack
 * No way out
 * Only accessable through MCPE Edit