Joey Loose Lips
First, Biden spouts off that somebody else was probably more qualified for the V.P. spot, and now he's rejiggering U.S. presidential history. From the LA Times' Top of the Ticket blog:

Declared Biden: "When the stock market crashed, Franklin D. Roosevelt got on the television and didn't just talk about the, you know, the princes of greed. He said, 'Look, here's what happened.'"

What's wrong with that, some might ask?

Well, for starters Republican Herbert Hoover was president when the stock market crashed in October 1929. Second, Roosevelt didn't take office until four years later. And, not to be picky, but there were also no televisions in use at the time. Radio was Roosevelt's favored medium.

(This was in the days before Roosevelt started blogging.)

Gregg just reminded me that Ford famously said in a debate with Carter that Poland was not a communist country. From a fun list of presidential gaffes on Wikipedia:

On October 6, 1976, during a televised Presidential debate in the 1976 Presidential election with rival Jimmy Carter, President Ford became confused and stated that Poland and Eastern Europe were not under the domination of the Soviet Union. When challenged over his comments, he repeated "There is no Soviet domination of Eastern Europe, and there never will be under a Ford administration."[2] In the words of Professor Alan Schroeder, author of Presidential Debates: Forty Years of High Risk TV: "That was a gaffe that took him some time to recover from--mostly because he did not back away from the statement".[3]