When Mac is informed that Vargas belongs to the Mossos d'Esquadra, he replies "Barcelona police". However the Mossos d'Esquadra operate in Catalonia as a whole, while the municipal police of Barcelona alone is the Guardia Urbana.
Vargas mispronounces his very own corps, the Mossos d'Esquadra, as "Mossos de Estrada". It was not pronounced Estrada by Vargas. It was pronounced correctly in Spanish. In Spanish, this "qu" is pronounced like /ca/ and can sound like /tr/ to someone not familiar with the Spanish pronunciation.
Jo explains that she knew of the Mossos d'Esquadra in 2004, when she still worked for the FBI and was sent to Spain to investigate the March 11 terrorist attacks. These attacks happened in Madrid but the Mossos d'Esquadra only operate in Catalonia.