- 1965-1970: Silver-clad planchets accidentally used for regular strikes (look for copper edge strip).
- 1971-D: Double Strike (off-center).
- 1972-D: Rare "No FG" (missing initials) error, very valuable.
- 1974-D: Doubled Die Obverse (DDO).
- 1976 (Bicentennial): Silver planchets used for regular issues (check edges).
- 1979-S Proof: "Filled S" mint mark (blurry 'S') vs. "Clear S" (clearer 'S').
- 1981-S Proof: Flat/Bulbous "S" mint mark.
- 1998-S: Matte Proofs from special mint strikes (SMS).
- 2002-P: Rotating Collar Break (collar chip).