Plot Hole: "Why don’t Marty’s parents realize they’d met their own son/remember what he looked like in Back to the Future (1985)?"

Explanation: "They knew him for a week over 20 years before he would look like that. And the only people he saw on a regular basis in that week were Doc, who knew, and Lorraine, who would be eager to forget a silly teenage crush she had just before meeting her soulmate."