An interesting (but not particularly scarce) type of coin error is the lamination flaw or planchet flaw error. It is also sometimes known as a peel error. A lamination or planchet flaw or peel coin error occurs when there is some sort of impurity in the metal of the coin planchet just below the outside layer of the coin. This impurity stops all of the metal in the coin bonding together correctly. Because the layer of impurity in coin is just below the surface the thin layer of metal between it and the surface can become become either partially or totally detached from the rest of the coin.
I am not sure if there is an official distinction between a lamination (or planchet) flaw error and a peel error, but I like to define them as follows:
Lamination/Planchet Flaw Coin Error: I like to think of this error as one where the thin layer of on top of the impurity metal from the coin has not really detached from the coin. These errors appear to have very slight flaws or cracks in the surface of the coin that generally are quite long.
Peel Coin Error: I like to think of this error as one where the thin layer on top of the impurity metal from the coin has completely or totally detached from the surface of the coin. In the above image you can see a peel on the reverse of the coin that is almost completely detached from the coin.
On a closing note, the lamination flaw coin error or peel coin error is closely related to the split planchet coin error. Both are caused my impurities or flaws of the coin planchet and result in all or part of the metal of the planchet detaching from the rest of the planchet.