"Across the Mexican Line" was the first of Solax's regular output of military pictures and, reportedly, the only one to be directed by Alice Guy Blanché. It's an unremarkable and dated one-reeler. Its main draw is that it was directed by the world's first female filmmaker. She began making movies in 1896 or thereabouts for the French studio Gaumont. In America, she and her husband formed the Solax studio. Although the output of other early cinema pioneers, like Georges Méliès and Edwin S. Porter, e.g., seems to have grown stale by the 1910s, Guy remained proficient throughout the decade, running her own company, but "Across the Mexican Line" is not one of her better productions. The acting here is broad and theatrical. The staging is equally theatrical, the settings are cramped, and it's mostly filmed by a series of long shots. The only cut to a closer medium shot in one of these scenes is awkward by later standards of continuity editing. As fellow IMDb reviewer Bob Lipton said, much of the story is told through the title cards. For instance, while Dolores turns away from the American lieutenant's advances in the medium shot, a title soon thereafter informs us, "Dolores finds she really loves lieutenant Harvey but duty compels her to keep her word."
And, the story is a bland and jingoistic spy romance set during the Mexican-American War and with the added exotica for the era of an interracial coupling (and which rather gives a double meaning to the "Mexican line" title). Dolores uses her newfound skills in telegraphy to betray her Mexican countrymen and to save her beloved American. Harpodeon's print is missing some footage, which is filled in by text explaining the missing scenes--although they don't explain the seemingly poor use of crosscutting between Dolores on top of a telegraph pole and a shot of two soldiers firing guns. The editing suggests that they fired at Dolores, but the subsequent scene of her shows her apparently unharmed, and we don't see another scene of the two soldiers. Oh well. It compares poorly to, say, the crosscutting last-minute-recuse films of D.W. Griffith, from around the same time.