The Sherlock star admitted that viewers have mistaken his riding as fake in Steven Spielberg's First World War epic, in which he stars alongside Tom Hiddleston and Jeremy Irvine.
"I wasn't a rider, I hadn't done any since I was about 12," he said.
"Jeremy is the best rider out of us - he does it effortlessly. Whereas, people think we had our faces super-imposed onto our body doubles, which is rather irritating."
Despite doing some riding as a child, Cumberbatch, who plays Major Stewart, had to take lessons with co-stars Irvine and Hiddleston, where they learnt how to ride single-handedly, while holding weapons.
"I was just very bad at horse riding. It wasn't something that really took to me," he admitted.
"I got to the stage where I thought the horse probably wanted to do something else, and I couldn't get past my awkwardness about that. I thought, 'What are these things doing, being attached on the horse? It feels wrong'."
But the 35-year-old has now gained a newfound respect for the equine friends: "A new form of relationship comes with the respect gained by getting over that. You have to be respectful of the personality of the beasts."