Some people do not have their memories completely wiped.
https://www.psychologytoday.com/us/blog/feeling-too-much/201412/children-who-seemingly-remember-past-lives
In a training school I attended, the class was on the psychology of people's interpretation of what they 'see', how they can misinterpret.
A man burst into the door in the back, shots sounded. The instructor dropped.
During 'witness testimony scenarios' that followed, everyone in the class had seen a gun in the man's hand and said he
'shot' the instructor. When we had played even our mock trial, video playback revealed that the bursting into the room took everyone's attention, that a volunteer student had fired a blank pistol from his desk while seated, and that the man who had burst into the room, had only a banana in his hand.