Shayla Bagir, who plays the role of Ylliana, is Russian, as is the role. Her dad, Elmar Bagir, helped with translating portions of the dialog.
Isac Mourana, who plays the role of Maquaqua, is from Mozambique (like the writer/director, Val Gameiro) and speaks a little Xi-ronga.
On the day of the final callback, and right after Zachary Gosset finished his audition, the police stopped by to look for dead bodies because a neighbor called it in... the scene was from the final confrontation between the hero and the villain.
Val Gameiro met Bobby Sargent before shooting started on Amnesia, and after that all the action scenes in the film grew exponentially. And became markedly better.
The role of Jennifer was not in the script originally, but when when of the actors wasn't able to show up for their role, Jennifer (who was there for a minor role with no lines) ended up filling for that spot, and her character grew in scenes and importance. She was fantastic, and very helpful, and even ended up helping with makeup and special effects makeup.