I believe it is the mind playing tricks on you, as most of the things that it effects are very, very minor details, things easily confused, especially if somebody else plants a bad seed first.

If the Mandella effect were actually real, nobody would agree on anything. This world would be a crazy mess of everybody with different memories of BIG things, which is not the case. Some people would remember Ronald Reagan being assassinated, some people would remember entire countries being nuked, etc, etc... Not whether a cartoon character from the 50's had pants or not. BIG things. These big alternate reality timelines don't seem to exist.