I was just discussing this with someone just the other day. Is the show called "Sex in the City" or "Sex and the City"? The reason the Mandela Effect was even brought up was because they called it Sex in the City. The truth is, I normally would have never corrected the person, because it's just not that big of deal. But it's an interesting study in how we think and remember. We repeat things wrong all the time and it just becomes fact in our minds.
How many times have I heard someone come into the Christianity Forum and claim to be sharing scripture...but it's not even scripture. They would bet their bottom dollar it was. But a search, would prove it never was in the Good Book. It was not that someone was taking scripture away and out of the bible. It's just people always thought the first time they heard the words quoted, that it was in the bible and they never learned any different.
Now if you believe that the news media messes up and makes false claims...I will agree. But I also know that I thought I heard that someone famous died, later to hear that they were alive and well, and after much thought realized I had my actors names mixed up with their faces. So I think it's a little of both.