Movie mistake

Hi I'm Ryo. I write about movie mistake this time. Movie mistake is Animation which contradiction in movie is pointed out. And I'll show you movie mistake related to Back To The Future at which we are looking. Please look movie mistake of Back To The Future.
In this scene, first, jar of candy which besides Marty is full. But second, full jar of candy is half empty...Oh!? Inconceivable!! Marty ate half of candy in this short time!? He is big eater. You might have seen movie mistake like this before.Well, I think that finding movie mistake is one how to enjoy movie. So you be careful when you see movie.　There may be a new discovery.