The villain Charles Muntz has a similar name to Charles Mintz, the Universal Pictures executive who in 1928 stole Walt Disney's production rights to his highly-successful "Oswald the Lucky Rabbit" cartoon series. This led Walt Disney to create Mickey Mouse, who soon eclipsed Oswald in popularity.
Before the film's worldwide release date, Pixar granted a wish from 10-year-old Colby Curtin to see the movie before she died. Colby had been diagnosed with cancer and was too sick to go to a theater. A Pixar employee flew to the Curtins' house with a DVD of the finished film and screened it for her and her family. Curtin died seven hours later at 9:20 pm, shortly after seeing the movie.
Even in storyboard form, the married life sequence that opens the film brought members of the production team to tears.
Co-director/co-writer Bob Peterson stated that Dug's line "I have just met you, and I love you," was inspired by a quote from a small child that he met when he was a camp counselor in the 1980s.
When Carl and Ellie go picnicking, their destination is a spot under the same tree from A Bug's Life (1998).