A coworker of mine brought this up to me a couple of weeks ago. Some examples he gave:
Some strange wording in the King James version of the Bible including mention of unicorns which he did not remember
The spelling of the name of Peanuts creator (it's Schulz not Schultz).
Wording of the Mr. Rogers Neighborhood song (I forget the specifics now)
Then of course there is the one that the effect is name for. Apparently many people remember Nelson Mandela dying in prison when in fact he did not.
Apparently one theory is that these false memories are a side effect of time travel.
The unicorn one is very strrange and funny, how can there be unicorns in the bible? There are a lot of this mandelas, i just hope we have bad memory, else the multi dimension or time-travel theories must be right which i think is more bad then the slippery memory :D