Agent Javier Pena, portrayed here by Pedro Pascal, was significantly involved in bringing down Pablo Escobar and the Medellin cartel in real life. These events are depicted in seasons one and two of Narcos. He was not involved in bringing down the Rodriguez brothers and their Cali cartel, which is depicted in season three of Narcos. However, the Narcos series shows Javier Pena in all three seasons as main character, bringing down the Medellin and Cali cartels.
Wagner Moura sees Narcos (2015) as his official entrance in the international film industry, because Elysium (2013) seemed more like an experience, since his character didn't have a big relevance.
Pedro Pascal felt uncomfortable in 1980s fashions ("I looked like a kid.") so he decided to make Peña's wardrobe a character trait: "Let's just say Javier Peña is like Don Draper, in that the 70s is where he really found himself... and so he's stuck there. He's not throwing those pants out, he's not changing his hair, he's not changing his shoes. It's his time, and he's gonna look like that until the day he dies."
Season 1 and 2 take place between 1979-93 with Season 3 picking up in 1994.
The dialogue was originally planned to be entirely in English, but the producers decided shortly before filming to switch to Spanish. This left the Brazilian lead actor, Wagner Moura at a loss, as he didn't speak the language. He wound up moving to Colombia for the few months before production and took a crash course at the local university.