I like novel films, but they have to work. The premise of this film is the ability to reverse entropy, to essentially move backwards in time. But for it to work, what was done forwards, must be rewound to the initial entropy reverse exactly, otherwise the whole idea of the film falls apart. But just doing same thing backwards would make for a boring film so the screenwriters break this "tenet" to make the film interesting. Didn't understand why they needed to wear masks to breathe, but their metabolisms worked fine and they didn't suck poo outta toilets with their bums!! :)