The main inspiration for the make up design for both tribes at the Stone Age scene is:
1) The Asaro tribe from Papua New Guinea (for the ''Omar tribe'')
2) A mixture between some tribes from Ethiopia and Papua New Guinea such as the Karo and ''The Walking Dead'' (for the ''David's tribe'').
The point was to make them look primeval and scary. Ethiopia is were it's believed the human race comes from, and Papua New Guinea is one of the last spots at the world to have cannibal tribes.
First collaboration between Marco Huertas and Cesc Nogueras. They would co-fund Bonzo [es] next to Al Pagoda one year later.
Ramón Langa was cast as 'David' but had to drop out days prior to start shooting due to scheduling conflicts.
The original cast for the battle scene was meant to be MMA fighters vs. contemporary dancers.
Thanks to the action choreographers Manu Pons and Alex Franco (The Natives) and the commitment of the actors, the one minute sequence shot from the tribal battle scene was accomplished in just 3 takes. After each take the art department had to repair most of weapons and costumes.