Sir Daniel Day-Lewis took the role as his wife, Rebecca Miller, was the writer and director. In preparation for the role he spent as much time as he could away from her.
During filming, Sir Daniel Day-Lewis arranged to live separately from his wife to achieve the "isolation" needed to focus on his own character's reality.
In a December 2021 New Yorker profile of the actor Jeremy Strong, Michael Schulman writes that Strong was an assistant to Daniel Day-Lewis during this movie's shoot. Strong started to mirror some of Day-Lewis's notoriously immersive acting techniques in the execution of his assistant's job. Schulman wrote: "During the [Canadian] shoot, Day-Lewis lived in his own cottage, away from his family. Since his character wastes away from a heart ailment in the course of the film, he starved himself, eating a meagre vegan diet, and became so emaciated that Miller was alarmed. Strong had driven up in his father's car. Strapped in the passenger seat was Day-Lewis's prop mandolin, which Strong recalled handling 'like a knight errant guarding a relic.' Strong had turned down a chance to act at the Williamstown Theatre Festival, which, he said, felt in some ways like 'an abdication of my path.' But he realized that this was an opportunity to be 'the sorcerer's apprentice.' He told me, 'My job was essentially a disappearing act, to be unobtrusive and on hand and play along with the game of it. I kept a diary, and, when I looked at it once, later, the thing that was clear was that my antennae were completely alight and absorbent.' He got so engrossed in his menial tasks that some of the crew cruelly nicknamed him Cletus, after the redneck character on The Simpsons. 'His whole brain was focussed on Daniel Day-Lewis,' one person recalled. 'I never really saw him unless he was standing outside Daniel's trailer.' Miller remembered that Strong bought a lot of nuts and stashed them in Day-Lewis's refrigerator, 'when Daniel was trying to starve himself to death. He was so concerned about him getting thinner and thinner that he was feeding him up.' Strong remembered the nut story differently, but, out of fealty to Day-Lewis, who is fiercely private, he would not elaborate. Day-Lewis became an important mentor. Strong said, 'At the end of the summer, he wrote me a note that I have still, that contains many of what have become my most deeply held precepts and beliefs about this work, and which I have treasured and will treasure until I die.' (Strong wouldn't disclose what was in it.) Nearly a decade later, he was cast opposite Day-Lewis in Lincoln, as John Nicolay, the President's personal secretary. Nicolay was 'utterly devoted to Lincoln,' Strong said. 'Those were easy shoes to fill.' When Strong won his Emmy, last fall, he wore a floppy taupe bow tied loosely around his neck-nearly identical to the black bow that Day-Lewis wore to accept his Oscar for My Left Foot."
For this film, Rebecca Miller received Honorable Mention from MTV's 2010 The Best Female Directors Who Should Have Won An Oscar.
Sir Daniel Day-Lewis and Paul Dano appear in this film and There Will Be Blood together.