In her photo, Lina Romay is dressed like a typical Spaniard, with the lace mantilla from Spain - a delicate headdress that rises above the head and is held in place by a "peineta", or a large decorative comb. It is possible that Romay's European-descendant father's ancestry was from Spain. The traditional bull fighting custom is from Spain and, at some point in history, was adopted by Mexico.
The stately Saguaro cactus shown is native to the Sonoran Desert, which covers portions of California, Arizona, and Mexico. It often appears in films as an indication the setting is out west, though often in locations it doesn't actually grow.
The first Droopy cartoon that has Louie Schmitt and Gene Hazelton as layout artist and character designer; they previously worked for the three Barney Bear shorts from 1948 to 1949. Schmitt and Hazelton later would work with the later Barney Bear shorts from 1952 to 1954. Also, this is the first use of Droopy's name.
Although, much like Raquel Welch, Lynda Carter, and Rita Hayworth, Lina Romay was touted as a "Latina"; in reality, her father, Porfirio Romay was a White Mexican national of European descent whose ancestors had moved from Europe to Mexico. Romay's mother, Lillian Walstead, was Irish and Norwegian.
The sign reads "Bullfight today, bull burgers tonight." In real life, most bulls meet their demise in the ring. (And, therefore, the second clause of the sentence.)