Mr. Montague is the secondary antagonist in the film "Beverly Hills Chihuahua 3: Viva La Fiesta", though he didn't have much screen time. He was portrayed by Jason Brooks.
In the film, he is the manager of the rival hotel of the one where the film took place. Not much was known, but he was shown to have had Jenny work for him in return of paying her. Jenny stole and gave him an important document from the manager's office. In the end, Delgado had him dangling off upside-down from a rope. After being discovered by the hotel manager, Mr. Montague was presumably arrested.