Within the classic-era US commemorative coin series, there are several one-year type coins that feature a date/year of striking that does not match the anniversary year of the person/place/event being commemorated. Of course, there are the several multi-year issues that fall into this category, but they are not my focus here.
Following are the coins that bear a year/date unrelated to the person/place/event being commemorated:
1921 Alabama Statehood Centennial Half DollarAlabama was admitted into the Union in 1819 and marked the centennial of this milestone event in 1919. The following year, 1920, a bill was introduced in Congress, on behalf of the
Alabama Centennial Commission, that called for a commemorative half dollar in honor of the State's 100th anniversary. The bill became Law in 1920, but the commemorative coin was not struck until October and December 1921 - the coins feature "1921" on their obverse. Two years late, but who's counting?!
1936 Landing of Swedes in Delaware TercentenaryPassengers from the Swedish ships, the
Kalmar Nyckel and
Fogel Grip first set foot in present-day Wilmington, Delaware in March 1638. Delaware staged an impressive celebration for the 300th anniversary of the event, including having Swedish Royalty attend the event; the anniversary was officially celebrated on June 27, 1938. The coins marking the event, however, were approved in 1936 and the bill enabling the coins specified that the coins were to bear the 1936 date regardless of when coined; the coins were struck and released in 1937.
Battle of Gettysburg 75th AnniversaryThe Battle of Gettysburg took place July 1-3, 1863. The 75th Anniversary of the critical US Civil War (CW) battle was marked in 1938 with a large Blue & Gray Reunion of CW veterans at the battlefield in Pennsylvania. The Pennsylvania State Commission had successfully lobbied Congress for a commemorative half dollar to support the anniversary; the bill authorizing the coin was signed into law in June 1936. The bill stated that all coins struck would "bear the date 1936, irrespective of the year in which they are minted or issued." So, the 1936-dated coin (struck in 1937) celebrated a 1938 anniversary!

There are other types of date mismatches, but I'll save those for a future post. Did I forget any of the coin date / anniversary date mismatches?