Christopher Lloyd is opening up about an almost very different “Back To The Future”.

Speaking with GQ, Lloyd recalled how Eric Stoltz was originally cast as Marty McFly.

It was six weeks into production when Michael J. Fox replaced Stoltz after the production team felt he wasn’t right for the role. Fox could only work on “Back To The Future” at night as he had commitments to “Family Ties” during the day.

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“Stoltz is a wonderful actor. I had no idea the change was coming,” Lloyd told the publication. “One night we were shooting the mall beginning sequence, and we were asked to come to one of the trailers at one o’clock in the morning. [Steven] Spielberg was there and he made the announcement of the change.”

“My biggest fear, because I was really working to get Doc right, I thought, ‘I don’t know if I can get it up to do that again. So I was worried about it. But, it all worked out,” he continued.

“They just decided that they needed somebody with a comic flair,” Lloyd said. “Michael, we had a chemistry which lasted the whole time.”

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The film is now cemented in cinematic history as a classic.

“Kids who saw it when the film first came out, grew up and had kids who they began their lives with it. So many people have come up to me to say how I’ve made their childhood, or the film made their childhood, or they became engineers or scientists or surgeons or whatever from the effect of the film on them. Nothing else I’ve done has had that kind of impact,” Lloyd concluded.