The actor’s co-star Felicity Jones was injured during the making of their latest film.
The duo, who starred together in The Theory Of Everything, reunite for The Aeronauts, about the fight for survival during a balloon flight in pursuit of discoveries about the weather.
Arriving at the movie’s premiere at the BFI London Film Festival, Redmayne said: “The crash was intense, I’m not going to lie.”
The film, out on November 6, is based on the true story of Victorian pioneers who took off from the Stafford Road in Wolverhampton, close to the current science park site.
After a near-death experience they managed to crash land in fields in rural Shropshire, some 25 miles away.
The craft used in the film were created by veteran balloonist Per Lindstrand, who won a £250,000 contract to manufacture them at his Oswestry-based Lindstrand Balloons.
See the trailer for The Aeronauts here:
They bring an authenticity to the film that also had a profound impact on the actors involved – and also brought the potential dangers into sharp focus.
Redmayne said: “The amazing thing about ballooning is you go from total peace – particularly gas air ballooning in which there is no noise, i’s complete silence and you’re basically just sitting in a log basket – to total carnage within a split second.
“So we came thundering down and crashed into these trees and then the basket crunched to the ground and we were flung back and in the basket in the film is a campaign chest, a big piece of furniture, and Felicity’s head smacked against the piece of furniture and there was this ominous silence.
“But fortunately she lived to tell the tale and then, going into the rest of the film, we had a sense of the real danger, no acting required. Genuine natural fear.”
Jones described the balloon crash, which took place on the first day of filming, as “a pretty hairy experience, I have to say”, adding: “You think it’s going to be fine we are going to go up in a balloon and they will somehow have figured out some safety measures but there are no safety measures at all, we were just up in the sky and it was pretty scary.”
However, she said filming Star Wars movie Rogue One directly before left her better prepared for the physical challenges of the role, adding: “I was a little bit more prepared this time and knew what I was getting myself into but you just have to throw yourself into it, that is what I’ve realised, you sort of start off thinking ‘Oh I will just do every other shot’ and by the end you’re just completely gung ho and trying everything out.”
Describing the physical challenges she faced, including scaling the side of the balloon, she said: “It was enormous, one of the most physically challenging things I’ve ever done and by the end I was completely covered in bruises and battered and worn out.
“It was a bit like shooting The Revenant or something, we wanted an absolute naturalism and with that comes at a great physical cost.”