We hear the (imitation) singing voice of Bing Crosby. A dog looks and sings like Rudy Vallee. The title song (by Joseph A. Burke and Al Dubin) makes reference to Russ Columbo, but we don't hear him mimicked or see him caricatured.
Crosby, Columbo, and Vallee (1932) (1932 March 19). An American Indian boy rides his canoe down a staircase waterfall. The canoe conforms to the fall's shape as he goes down.
Holland Days (1934) (1934 January 12). Farmer Al Falfa's ship conforms to the shape of the waterfall.