Among Back to the Future fans, it’s a well-known fact that Michael J. Fox wasn’t the first actor cast as Marty McFly. Eric Stoltz had already shot a significant portion of the film before producers decided it wasn’t working out. They fired him and went back to their first choice, Fox, who’d been unavailable due to scheduling conflicts.

You wouldn’t know that just by watching the film, as all of Stoltz’s scenes were re-shot with Fox. However, if you were looking really, really carefully, you may have noticed a tiny bit of Stoltz’s footage remains in the finished film. Find out where you can see Eric Stoltz in Back to the Future after the jump.

Too Old to Grow Up put together a video explaining this little-known bit of Back to the Future trivia.

Stoltz’s footage is hard to pick out, since his face doesn’t actually make it into the film. (The filmmakers are professionals, after all — they wouldn’t be that sloppy.) Turns out, though, that that’s his fist flying at Biff Tannen in the 1950s diner, as has been confirmed by actor Thomas F. Wilson himself. After all the time we’ve spent wondering what Back to the Future would be like with Eric Stoltz in it, it turns out we technically knew the whole time.