Time travel is inherently difficult to bring off convincingly, and it's extraordinarily hard to avoid paradoxes, and to deal with "butterfly effects" in a rigorous and coherent way.

Exactly, like the "grandfather paradox". Taking into consideration that alterations in time travel can lead to massive inconsistencies: just like someone going back in time to kill his grandfather before he met his grandmother, it will prevent the person from being born right? Now the question is; if the person isn't born, how did he go back in time? Okay that's kindda like a time loop.

I'm a fan of science fiction, even though I'm not a fan of series but I've seen quite a few of them like flash, legends of tomorrow, teranova etc. With the way you've reviewed this series, I'm already piqued to watch it.
Nice review