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.
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.
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 Bichos: Una aventura en miniatura (1998).