I love finding Easter Eggs in films, and some of them are unintentional bits like catching an extra doing something embarrassing in the background or things like that.
Well in the epilogue of Back to the Future Part 3, Doc returns to let Marty know he is alright and he does so much into his own future. In fact he has two young boys with him that he calls Jules and Verne. The young actors who play these boys are nothing more than extras who stand in for the bit. But it seems something strange is a foot with Verne that I never noticed before.
He waves for attention then points at his boy parts! And its caught in the scene.
It is entirely possible this boy isn’t some creative pervert who wants to gesture at his bits hoping it would get caught on film, but it is possible the kid was signaling to someone that he really had to go pee.
Either way, its something I never noticed before.