Dorr was cast in two Hollywood comedy shorts, both released by Path Exchange (RKO) in 1930: All Stuck Up and Ride 'em Cowboy; then for the remainder of the 1930s, he demonstrated his abilities at portraying an array of characters such as hotel clerks, police officers, reporters, and many more, under contract as a "day player".
He soon was cast in two Hollywood comedy shorts, both released by Pathe Exchange (RKO) in 1930: All Stuck Up and Ride 'em Cowboy. For the remainder of the 1930s, Dorr demonstrated his abilities at portraying an array of characters, such as hotel clerks, police officers, reporters, office workers, elevator operators, salesmen, bank employees, cowboys, mob henchmen, prisoners, truck drivers, train crewmen, soldiers, sailors, and hospital personnel. He was cast, often under contract as a "day player", in more than 250 films in just the 1930s alone, remarkably averaging a different role in a different film every two weeks for ten straight years. 
