Paintings of his were included in 1994's The View from Within: Japanese American Art from the Internment Camps, 1942-1945 at the Japanese American National Museum, in Los Angeles; and in 1995's Japanese and Japanese American Painters in the United States, 1896-1945: A Half Century of Hope and Suffering, which showed in Japan at Tokyo Metropolitan Teien Art Museum, Oita Prefectural Art Hall, and the Hiroshima Museum of Art.
Their home became a meeting-place for Seattle's arts community, including prominent Japanese-American artists Kenjiro Nomura and Kamekichi Tokita, whose mastery of calligraphy was an important source of the Asian influences in Callahan's artwork.