RKO bought the rights to the French version Michel Strogoff (1936) for $75,000, and specifically signed its star Anton Walbrook so that they could use some scenes from that movie. About 22 scenes were edited into the new version, including Siberia footage, battle footage, Tartar camps and the river on fire. The Hollywood Reporter mentioned that the new footage shot blended perfectly with the old footage.
At the end of the movie, both Anton Walbrook and Fay Bainter are introduced as "two new RKO Radio Pictures personalities."
The TCM print had an onscreen copyright statement which read "copyright 1945 by Ermo Productions." It suggests that associate producer Joseph N. Ermolieff obtained the rights to the movie and modified the title page. All other onscreen credits, however, agreed with those listed in the AFI Catalogue and the IMDb database.
French author Jules Verne, better known for his futuristic and fantastic works, actually penned the novel on which the film's screenplay was based.
Secret codes, as shown, were the standard method of delivery for critical, sensitive information sent by operatives. A different variation would be seen three years later in the film Comrade X (1940).