Writers assignments (from Republic Pictures Corp. files): Norman S. Hall--Chapters 1 and 6. Joseph F. Poland--Chapters 2, 7 and 11. William Lively--Chapters 3 and 8, Ronald Davidson--Chapters 4, 9 and 12. Joseph O'Donnell--Chapters 5 and 10. This order is also the writers' order as seem on the film (minus the chapter assignments.)
Chapter Titles: 1. The Fifth Column Strikes; 2. Dead End; 3. Man Hunt; 4. Trapped; 5. Test Flight; 6. Double Danger; 7. Death Takes the Witness; 8. Counterfeit Trail; 9. Ambush; 10. Sky Raiders; 11. Trail of Death; 12. Code of the Rangers.
The budget (expected cost) of this serial was $138,536. The actual negative cost was $139,701. The film came in at $1,265 over budget.
Body count: 22
The parachute scene in Chapters: 6 and 10, is taken from King of the Royal Mounted (1940). In Chapter 10, the scene is reversed-imaged once, to make it look like two different men are jumping.