I think you have to be a special kind of daring person to be an actor or filmmaker. Maybe even a special kind of crazy. But on the actor side, one thing that I can appreciate is good casting. If you are not an actor here is quick definition of casting. It is the assignment of parts and duties to actors or performers.
Now with that, what makes a great casting decision? It can be any number of things. But most of the time, a great choice won’t make itself known until the final product is seen.
For example, in Back to The Future, the role of Mary McFly was cast with Eric Stoltz. Michael J. Fox couldn’t get out of his schedule with the television show Family Ties. Eventually, this was cleared up, and after filming a few scenes, it was clear Eric Stoltz was not the right fit. This wasn’t a screen test, he was going to play the role. Four weeks of shooting were scrapped, and the film had to reset. That’s not cheap. The instinct to get Michael J Fox prevailed.
It was known that Eric Stoltz, while a very gifted actor, was not hitting the comedic beats that the producers and director were looking for. It goes to show the first casting choice was right the first time. Although making a hectic schedule for Michael J Fox, the film is now a part of a classic trilogy. It would be hard to imagine anyone but Fox in the role.
As a minor Easter egg, Eric Stoltz was in the film but for a mere snippet. Here is a video that shows the evidence.