Many types of mint errors are missed by inspectors and are inadvertently released into circulation. Clipped Planchets, Off-Center Strikes, and Wrong Planchets are just a few examples of the many types of error coins that slip out of the mint occasionally. Some errors are fairly common, but many are extremely rare.
1906 Liberty Nickel struck on a cent planchet. Well centered with a very clear date. Exceedingly rare, super cool, and almost certainly unique!
Struck 10% Off Center.
Washington Quarter struck on a clad dime planchet. Full date!
1975 Lincoln Cent struck on a clad dime planchet.
Jefferson Nickel struck on a cent planchet.
Washington Quarter multi struck with an obverse indent. A wild error in super high grade.
A very high quality and very deep Obverse Die Cap.
Cent Struck Over a 2001-P Dime. Traces of the dime design are visible including the outline of Roosevelt's head and some of the under-type. A very exciting mint error!
Struck on a struck Lincoln Cent. Flip-flop strike. The under-struck Lincoln is easily seen. Rare, very high quality, and very cool!