These three cards use the same Ferry Building image. Because the Cardinell-Vincent and Pacific Novelty cards use the same stock number S.F. 55 and the same text, I'm guessing the companies were related by 1918 (presumed date of the Pacific Novelty card). The "Evening hour" setting features a sunset-colored sky to the northeast, unlikely but not out of the question. The tower featured an illuminated "1915" during the P.P.I.E. (and later displayed "1925" for the Diamond Jubilee and "1915" once again for the 2015 P.P.I.E. centennial), but I believe the "1918" on the Pacific Novelty card is purely the work of the postcard artist, and poorly executed at that. My Ferry Building page and my postcard catalog show many additional images. Image credit on front: © R.J. Waters & Co.
In addition to the "1915" on the tower, the Mitchell and Cardinell-Vincent cards show a large letter "... Invites the World..." sign mounted on the roof, facing the Bay. That sign is absent from the other postcards on this page, possibly because they used earlier images or because the postcard artist thought the Evening Hour setting looked better without it.
Steve's SF postcard pages: