Christopher Lloyd regrets not attempting train stunt while filming Back to the Future Part III

Christopher Lloyd regrets not attempting to jump from a horse to a moving train himself while filming Back to the Future Part III.

In his new memoir, In My Own Time, the Doc Brown actor explained that he was allowed to ride on horseback alongside a speeding steam train for the climactic sequence, but he then had to let a professional stuntman take over.

"The scene called for me to ride my horse right up next to the rear of the train, until I was close enough to grab a handle on the car. However, I was plainly told not to actually grab that handle - in no way should I try to do that, or pull myself off the horse and onto the train," he recalled in the book, according to Entertainment Weekly, noting that there was "too much risk" involved in doing it himself.

However, when the time came to shoot the scene, Lloyd became very tempted to complete the stunt himself.

"The train is hurtling along at some fantastic speed, and I'm so close I can feel it going whooooosh as it rattled alongside me," he remembered. "I was within reach. And I just felt, I can do this. It's there. I almost put everything in jeopardy. But I didn't, and that was a close call."

Lloyd, now 88, admitted that he still wonders what would have happened if he'd given it a go.

"Who knows what would have happened next? But whenever I watch the movie and see that scene, I still feel that pang in my heart: I should have done it," he added.

Lloyd played Emmett 'Doc' Brown alongside Michael J. Fox's Marty McFly for three Back to the Future films between 1985 and 1990.

In the book, which is out now, the Taxi actor shared that the third instalment is his favourite.

"People ask me all the time which of the Back to the Future films I like best, and I have to say it's Part III," he confessed.