The two Brits, who previously co-starred in "The Theory of Everything", reteamed to portray 19th-century hot air balloon enthusiasts James Glaisher and Amelia Wren in the Amazon movie, and Redmayne admits he has never been so terrified on a film set as he was the day they ran out of sand while floating above the trees.
"It was all actually very peaceful and serene until the landing," Eddie tells U.S. chat show host Ellen DeGeneres. "There were helicopters and drones coming around (filming) and then they left once they (camera operators) got what they needed and we just crashed into a forest..."
"Basically, these old gas balloons, you only use sand... You let the gas out when you want to land and then you pour sand to go up a bit higher and we ran out of sand. We survived."
In fact the only major injury on the set came when clumsy Eddie tripped over a mat laid down for his own protection.
"They had this crash mat to save you from hurting yourself if you fell out of the air balloon and one day I was walking on to set and I tripped on it," he laughed.
"The worst thing was they took me to hospital... and in this scene I has frostbite and I had blood all over me - it was quite intense - and I arrived at hospital in this wheelchair... and they're all like, 'Oh my God, what's happened to him?' "