[2] He was uncredited in Stella Dallas (1937), Souls at Sea (1937), Make a Wish (1937), The Adventures of Tom Sawyer (1938), Judge Hardy's Children (1938), Lord Jeff (1938), That Certain Age (1938), Little Tough Guys in Society (1939), The Spirit of Culver (1939), Confessions of a Nazi Spy (1939), Babes in Arms (1939), First Love (1939), and Joe and Ethel Turp Call on the President (1939).

[3][4] McCallister could also be glimpsed in Susan and God (1940), Henry Aldrich for President (1941), Dangerously They Live (1941), Always in My Heart (1942), Yankee Doodle Dandy (1942), Spy Ship (1942), Night in New Orleans (1942), That Other Woman (1942), Gentleman Jim (1942), Quiet Please: Murder (1942), Over My Dead Body (1942), The Hard Way (1943), and The Meanest Man in the World (1943).

"[2] At 20, he appeared in the World War II morale booster Stage Door Canteen, where he played a star struck serviceman with theater actress and producer Katharine Cornell.

[5] McCallister leapt to fame playing the lead as Sparke in the horse-racing tale Home in Indiana (1944), also starring Walter Brennan and Jeanne Crain.

He appeared with Edward G. Robinson in 1947's The Red House and had the star role in Thunder in the Valley (1947), and supported June Haver in Scudda Hoo!

McCallister began appearing on TV in episodes of Suspense ("Lunch Box", "Collector's Item"), and Lux Video Theatre ("Down Bayou DuBac").

McCallister and William Eythe were producers of the stage musical revue Lend an Ear, which began at Los Angeles' Las Palmas Theater and launched Carol Channing's career.