10 Infamous Movie Plot Holes That Have Simple Explanations
3. Why Don't Marty's Parents Recognise Him 30 Years Later? - Back To The Future
The "Plot Hole"
Given that Marty McFly (Michael J. Fox) was so pivotal in ensuring his parents George (Crispin Glover) and Lorraine (Lea Thompson) got together, why didn't they recognise him as their son 30 years later?
The Explanation
Given that Marty spends just around a week in 1955, it's completely believable that even Lorraine, upon whom Marty left a clear impression, would have only a faded memory of him some three decades later.
Memory is notoriously unreliable, and even if Lorraine and George saw a resemblance between their son and "Calvin Klein," there are literally hundreds of explanations a rational person would settle on before accepting the whole time travel premise.
In a recent interview, the film's co-writer Bob Gale confirmed as much:
"Bear in mind that George and Lorraine only knew Marty/Calvin for eight days when they were 17, and they did not even see him every one of those eight days. So, many years later, they still might remember that interesting kid who got them together on their first date.
But I would ask anyone to think back on their own high school days and ask themselves how well they remember a kid who might have been at their school for even a semester. Or someone you went out with just one time. If you had no photo reference, after 25 years, you'd probably have just a hazy recollection.
So Lorraine and George might think it funny that they once actually met someone named Calvin Klein, and even if they thought their son at age 16 or 17 had some resemblance to him, it wouldn't be a big deal. I'd bet most of us could look through our high school yearbooks and find photos of our teen-aged classmates that bear some resemblance to our children."