17 days before shooting was to commence in Morocco, none of the characters had been cast. The production crew made an announcement in the nearest town via television and radio and in the mosques that actors were needed. Within the next 24 hours, over 200 people showed up hoping to participate. Almost all of them are in the final cut of the film, both as principal characters and as extras.
The scene where Chieko (Rinko Kikuchi) and her father are in the car together was shot without filming permission from the city due to slow Japanese bureaucratic procedures. The crew created "man-made" busy traffic, and began shooting the scene. Later the police started chasing them while still shooting the scene.
Director of photography Rodrigo Prieto encountered a problem while filming a track shot where Richard and the villagers carry the wounded Susan to the top of a steep hill: he tried running backwards to get the shot, but each time he tripped, often falling. However, director Alejandro González Iñárritu ruled out using a Steadicam and insisted on hand-held camera work. Finally, key grip Joseph Dianda came up with a solution: Prieto filmed the shot while seated in a hotel chair carried by four grips. The resulting footage became known to crew members as "The Joey Chair Shot".
Only Richard and Susan's segment was shot on 16 mm film; the rest of the movie was shot on 35 mm. In the scene where the helicopter finally arrives at the village, there is a slight pause as the 35 mm format kicks in.
The shallow depth of field in Chieko's sequences is a nod to the photography of Mona Kuhn. Most of Kuhn's photos have shallow focus, a concept used by the filmmakers to emphasize Chieko's deafness and isolation.
The trivia items below may give away important plot points.
Actress Adriana Barraza, in real life, has had a long history of heart problems including two minor heart attacks. Despite this, she still insisted on carrying co-star Elle Fanning around in the desert for the two days of filming of Amelia walking in the desert with Mike and Debbie.
The color red is prominently seen in all four segments of the film. For example, Yussef, the Moroccan boy who accidentally shoots Susan, wears a red jacket that says "Morocco" on the back, while Amelia wears an elaborate red dress, causing her to stand out; Chieko frequently uses a red pen to write notes to people who can't understand sign language, and the seats on Richard and Susan's bus are red.