Javier Bardem's part in this film is the first time that a performance entirely in the Spanish Language has been nominated for an Academy Award Best Actor Oscar.
When Alejandro González-Iñárritu was casting the role of Ana at a school, Hanaa Bouchaib came up to him, grabbed him by the shirt and said: "Are you the one who's making the movie? I want in" The director said that he was so captivated that really kept her in mind.
Alejandro G. Iñárritu wrote the role of Uxbal specifically for Javier Bardem. The director said that when Uxbal first came into his mind, Bardem was the only choice that made sense.
The audible heartbeats in the scene where Uxbal hugs his daughter were achieved on set with microphones stuck to the actors' skin while they hugged.