So, a perfectly fine premise, well-acted, somewhat wrecked by the writers not thinking things thru at all. First hour I was fully on board, then nothing added up, and by the end I was annoyed. As with so many films, the color has been shat on with the orange/cyan filter, except where day-for-night scenes are grey filtered.
SPOILER land
There are two hypotheses about time travel. A is that everything forward and back has already happened, and if you vanish in the future it's because you already appeared in the past; you may be the cause of events but they can't be changed. This is the only rational argument, really. We know time is just part of space-time; each tick moves things "ahead" in the next frame.
B is that time travel rewrites the future; you kill a fascist and fascism vanishes and everyone's singing Kumbaya. But then there's no need for a time machine and assassin, so the fascist isn't killed and fascism spreads. Now you need a time machine again. This is madness.
The movie seems to be doing hypothesis A, but then ends as if hypothesis B happened. But only after decades of the original timeline.
Second, somewhat worse, is that the method of killing is preposterously convoluted. Why does the assassin need to inject targets now so someone in the future can push a button? She could just shoot them or give them a drug OD and not provide weird clues to make a cop go all Zodiac case on it for decades. I am disappointed the cop doesn't have a clue & string board in his car.
Third, completely nonsensical stuff about the Super Moon being a bridge between worlds or some shit. Absolute astrology-class woo nonsense.
Fourth, the idea that some newsletter about "real Americans" and a flag with 5 badly-placed stars is going to incite the Second Civil War, completely fails to understand our first Civil War, and the nature of populist movements. You'd have to kill millions to stop it.
Fifth, the idea that you'd use this to stop some bombings, no worse than what dozens of countries endure every day, including several at the hands of the US armed forces; rather than going back to stop Hitler, or Stalin, or Mao, or Pol Pot, or Nixon.
The writers previously worked together on Limitless, an equally vapid show about the "10% of your brain!" myth. I can't find their ages, but I'm pretty sure they're under 30, it has that earnest political certainty & lack of humor or irony. They've clearly never read a history book, especially none of the Presidential biographies they show.
★★☆☆☆ — definition of competent but unenjoyable.