Disclaimer on film and connected paper - Note: Care has been taken to prevent any costume of the production from being accurately that of either side in the Spanish civil war. The story does not attempt to favor any cause in the present conflict,
The original title of this film was "The River is Blue" and the original director was Lewis Milestone. Kurt Weill even wrote music for the original project that was never used (lyrics by Ann Ronell). The title was changed to "Castles in Spain," then to "Blockade." The topic of the Spanish Civil War was politically sensitive and there is some hint that the upheavals of the original project were due to the political content of the film.