The Key to Yesterday was the first production of actor Carlyle Blackwell’s Favorite Players Film Co. (named after the Famous Players Film Co., for whom he had previously worked), and the first release of the new Alliance Films Corp. (Alco), a company offering a program of multiple-reel releases every week. Max Blackwell, Carlyle’s brother and Favorite Players’ general manager, told the 10 Oct 1914 Moving Picture World that their policy was “to produce films from well-known books.” Favorite Players, it turned out, released only four movies. The other three were The Man Who Could Not Lose (1914, see entry), The Last Chapter, and The High Hand (both 1915, see entries).
       According to a 17 Aug item in the 29 Aug 1914 Motion Picture News, Blackwell had leased the Norbig studio on Allesandro Street, in what was then called the Edendale section of Los Angeles, CA, formerly used by Bosworth, Inc., and the Famous Players. Filming was said to be underway on the ‘The Key to Yesterday,’ expected to be four reels in length. Location shooting was scheduled to take place in Pine Ridge, CA, according to the item; however, two weeks later, the 5 Sep 1914 Motography reported that Blackwell had gone to Pine Crest, CA, to film outdoor scenes before traveling to San Diego, CA, "for his sea and ship matter.” (The earlier reference to “Pine Ridge” may have been mistaken.) At the end of that month, the 26 Sep 1914 Moving Picture World reported that the members of the film company were back in Los Angeles after shooting "revolutionary scenes" in Tucson, AZ, directed by Carlyle Blackwell. On 19 Sep 1914, New York Clipper noted that Blackwell had “completed” the film.
       A full-page advertisement in the 10 Oct 1914 Moving Picture World announced that along with the main actors, The Key to Yesterday featured “One Hundred Others.” The 17 Oct 1914 New York Clipper listed the film as playing at New York City’s Lexington Theater that week.
       Reviewer Rev. E. Boudinot Stockton, in the 17 Oct 1914 Moving Picture World, wrote, “The story is an involved one, and although the screen version has simplified it much, it still remains a difficult one to tell and the faults of the picture are almost if not entirely due to this fact.” The 24 Oct 1914 Variety complained that it looked like a five-reel film that had been trimmed down to four reels, leaving “voids in the story that the lack of captions does not permit the audience to pick up.” Otherwise, both reviewers were positive about the movie.