[2] Set in the years prior to America entering World War II, the plot is slightly anachronistic in that the serial features a mix of period western and modern elements, which was not unknown in the B-Western films also produced by Republic.

Tom teams up with Sally Crane (Pauline Moore), a reporter who witnessed his father's murder, and Mexican officer Lt. Pedro Garcia (Duncan Renaldo).

The saboteurs plan to destroy the Whitney Dam would flood the oil fields in Texas, and when Sally finds one of their hideouts, Tom has to rescue her.

King of the Texas Rangers was filmed in the Big Bear Valley, San Bernardino National Forest, California between June 17 and July 18, 1941.

However, according to co-star Kenne Duncan, Baugh turned out to be a good horseman (he was raised on a ranch, in Texas), took direction well and learned about acting quickly.

[8] In the opinions of researchers Jim Harmon and Donald F. Glut, King of the Texas Rangers contains "one of the greatest cliffhangers of all time."