The Most Dangerous Game was filmed at night on the same jungle sets as King Kong, which was shot during the day, with Armstrong and Fay Wray simultaneously starring in both pictures.

Prior to World War II, in 1940, Universal Pictures released Enemy Agent, about countering a Nazi spy ring.

Later in that decade, Armstrong played another Carl Denham-like leading character role as "Max O'Hara" in 1949's Mighty Joe Young.

This film was another stop-motion animation giant gorilla fantasy, made by the same King Kong team of Merian C. Cooper and Ernest B. Schoedsack.

In the 1950s, he appeared as Sheriff Andy Anderson on Rod Cameron's syndicated western-themed television series, State Trooper.