What is the Mandela effect? And have you experienced it?

A lot of the article reminded me of the following...

"Hot air balloon flights and memory

In 2002, an experiment by Kimberley Wade at the University of Warwick showed people a photograph of themselves as a child in a hot air balloon basket. This was shown as “evidence” that they had been on a hot air balloon flight. The photos had been doctored in computer graphic software. The researchers had obtained a childhood picture of the experiment’s subjects, and the software cut out their childhood picture and placed it inside the image of a hot air balloon. "