There are two plaques at Merion Golf Club commemorating famous things that happened there. You probably know about the Ben Hogan plaque - it's in the 18th fairway at the site of Hogan's famous 1-iron shot in the fourth round in 1950. There's also a plaque on the 11th hole memorializing Bobby Jones' victory at the 1930 U.S. Amateur - the win that completed his Grand Slam.
But did you know that Merion originally screwed up both plaques?
The original Hogan plaque had the wrong date of Hogan's 1-iron shot. The shot happened on June 10, 1950. But the plaque Merion installed had the date as June 11. The erroneous plaque was replaced by a new one in 2000.
And the mistake on the Jones plaque was a real whopper. That plaque identifies Jones by his full name - Robert Tyre Jones Jr. Except that the original plaque gave his names as "Robert Trent Jones Jr." Trent Jones is the architect, not the golfer. Oops! Merion corrected that one by placing the correct name over the incorrect one through the use of a narrow metal strip.
You can see the errors pretty clearly by doing a photo search and comparing.
Let's hope if Merion ever installs a new plaque to commemorate another important event in the club's history that it does a little proofreading first.