Writer-director Isaac Ezban was influenced by '' The Twilight Zone '' . Like that show , he said he wanted to make a thriller that focused primarily on the characters . Ezban wrote the script in 2011 , and shooting began on 7 July 2014 in Mexico City and Puebla . Ezban considered shooting in black and white but instead used desaturated colors . Besides '' The Twilight Zone '' , Ezban was inspired by '' The Box '' , which he said looks otherworldly because of its desaturated colors . The film is not overly political , but Ezban wanted to include references to the Tlatelolco massacre as a plot point to homage the socially conscious films of the 1960s while giving it a uniquely Mexican flavor
Tlatelolco massacre
Tlatelolco massacre
The Similars