Owing to the box office success and continued popularity of The Sound of Music (1965), Plummer remains best known for his portrayal of Captain Von Trapp, a role he reportedly disliked.  He declined to attend the 40th Anniversary cast reunion, but did provide commentary on the 2005 DVD release. Plummer relented in 2010 for the 45th anniversary, and appeared with the full cast on The Oprah Winfrey Show on October 28, 2010.

Plummer said of the movie and his role in a December 2009 interview, “I was a bit bored with the character (of Captain Von Trapp), Although we worked hard enough to make him interesting, it was a bit like flogging a dead horse. And the subject matter is not mine. I mean, it can’t appeal to every person in the world." However, Plummer admits the movie itself was well made and, despite his reservations, is proud to be associated with a film with such mass appeal. "The world has seen (The Sound of Music) so many times. And there’s a whole new generation every year—poor kids—that have to sit through it (laughs). But it was a very well-made movie, and it’s a family movie and we haven't seen a family movie, I don't think, on that scale for ages. I don’t mind that. It just happened to be not my particular cup of tea.