Other mistake: Ferriman says he can only mark someone if they do something sinful first. Dodge shouldn't have been marked as he technically shot Ferriman in self-defense, which isn't considered a sin, but near the end Epps sees her dead crewmates and Dodge is also shown as well as marked.
Suggested correction: It was implied that if they sinned in their life they could be marked not immediately before death. That is also why the demon explained that he couldn't mark Katie because she never committed any sins.