One of the most fascinating behind-the-scenes Back To The Future details I recently learned is that Michael J. Fox’s Marty McFly was the result of a recast. Eric Stoltz originally earned the role and even played Marty for over a month with the rest of the cast before the swap was made. As you can imagine, the experience was “heavy” for everyone involved. Christopher Lloyd, aka Doc Brown, just revealed what it was like for him when Stoltz left and Fox was brought in. Lloyd just turned 88 years old last week, and is marking the Back To The Future-themed milestone (remember the DeLorean gets to 88 miles per hour to work) with an autobiography that’s now on bookshelves. While promoting his book In My Own Time, he reminisced about the moment on set when he learned Michael J. Fox was going to replace Eric Stoltz. As he said: I remember the night before the morning of your first day. We’d been working all night for a few days in the shopping mall, so lunch would be at like one o’clock in the morning. We broke for lunch, and we were in the parking lot of the mall, and somebody stood up to say somebody was going to make an announcement after lunch. We had our lunch and then we all gathered around one of the trailers. Spielberg, I think, got up and told us that tomorrow morning, Michael J. Fox is going to be taking over the role of Marty from… Eric Stoltz.In the new chat with the Family Ties actor for Interview Magazine, Christopher Lloyd recalled the moment he learned that Fox would take over Marty. It’s what he said next that I found quite interesting. In his words: That was pretty stunning news. Because for me, totally selfishly, I felt I’d given 99 percent every moment they shot for six weeks. I had to put a lot of energy into it, and I was still getting into the groove. My first thought was, ‘Oh my god, I’m going to have to do all that again. How am I going to do it?’ But it all worked out. When you came along, it was a whole different game. Your spontaneity, humor, smartness, and intelligence—it was great.I mean… imagine getting done with a month’s worth of work, and then being told you have to start from scratch with a completely new coworker you’ve just met. It’s frustrating news to receive, even if Steven Spielberg is the one giving it. But, as Lloyd also shared, “it all worked out” because Michael J. Fox was just perfect for the role. He offered a new burst of energy to the set Stoltz didn’t have, and what we got in turn is one of the best '80s movies ever. I would have thought that Lloyd would be worried about working with a whole new actor on Back To The Future. However, the reason instead was a fear from the actor’s side that he might not be able to replicate the performance he’d given thus far. Stoltz was reportedly replaced on Back To The Future because the actor was “a little more Shakespeare” than the filmmakers wanted, per Fox. It couldn’t have been easy for Fox to start playing Marty after the cast and crew had gotten into the swing of things on the set of Back To The Future. Plus, Fox got the role after making a deal that he would shoot the movie and Family Ties at the same time. It resulted in the young star not getting much sleep during the shoot, but it also helped make Back To The Future the beloved film it is. Back To The Future just crossed its 40th anniversary last year, and I love knowing there are always more stories to learn about the iconic film. I'm curious what other nuggets are in Lloyd's brand-new autobiography.