For the record, Jack's hallucinations are what PTSD is really like for some people. Until my recent therapies, I used to hallucinate about my younger self; each one represented a year of my life, each covered in burns and blood, asking me why nobody could save them. The horror of regret is one of the many hells of PTSD and living with it for years on end. Genndy and his team outdid themselves with Jack's mental illness and his struggle to overcome his own trauma and regrets.