Watch: Eric Stoltz is Still in BACK TO THE FUTURE
The fact that Eric Stoltz was originally hired to play Marty McFly is common knowledge to anyone who calls themselves a Back to the Future fan, but did you know he is still in the movie even after being recast by Michael J. Fox? This video lays out the whole story, and it's an interesting piece of trivia that even the most diehard BTTF may not have known about.
Since Robert Zemeckis had to reshoot four weeks' worth of footage, it's not too surprising that he ended up using a quick shot from before Fox came on board. It's unclear whether they shot the punch with Fox and it just didn't quite work as well, or if his busy schedule necessitated the editors to use an older take, but either way, they did a pretty good job hiding it if I've never noticed it after seeing the movie so many times.
Via: /Film