9. Why Wasnt Old Jennifer Expecting Herself?
When old Doc meets and talks to young Doc in Part Two it can be explained that old Doc simply forgot that his younger self had had a conversation with a random man he met on the street. That makes sense as the young Doc would have no reason to remember this interaction. What makes less sense is that the old version of Jennifer was shocked to see her younger self, and that it caused her to faint. Why wouldn't old Jennifer be aware of this? She surely would remember going in the time machine with Marty and Doc Brown wouldn't she? The Doc did his Men in Black memory zapper thing that he explained would make young Jennifer believe that her travelling in time was just a dream. She then woke up however and was trying to get out of her and Marty's future home in Hilldale. There's no way she's still think that was a dream, so why wouldn't the version of herself that was thirty years older know not to come in and make her younger self faint?