Memory is where our shared concept of reality breaks down. Three people share the same event and at the time see it as the same. 30 years later the same people talk about the event and there will be 3 rather different views of it. We lose bits of the memory over time - they are erased from out mind. The brain then fills in the missing parts with our other experiences and ideas.
Another example is a person has NEVER been to a place. If he/she is told by someone they trust many times that they where there, then when the experience is described, that person will remember being there.
As well if there is stress or trauma to the event, often every last person will have differences in how it happened. We are easy to bend what we know as "real".
The image you see if you know me you will more than likely know what you are seeing. Others will think it different. Some as well, who do NOT know me will see it as what it is.
It's actually amazing to me that we have a shared concept of reality that we all seem to agree on. I find that interesting.