There's a big Easter egg in Ep 13 "Leviathan" it's do with a famous city
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Ep 16 "Legendary" season Finale:
THE FINAL BATTLE – After the numerous sacrifices the team has made since the beginning of this ride, Rip (Arthur Darvill) decides that it’s time they each decide their own destiny and returns them to Central City a few months after they first left. Returned to their normal lives, each team member must individually decide if they are willing to sacrifice everything in order to save the world. Meanwhile, Sara (Caity Lotz) visits with her father (guest star Paul Blackthorne) who delivers some heartbreaking news about her sister.
season 1 will have definitive ending with season 2 having a completely different tone with new heroes and villains. I think if they do crossover to Gotham, this has been mentioned a few times, could be where the wave rider goes earth-2 which would suit the tone and style of Gotham.
this show has not been a disappointment and I think that is not based any dc comic but uses characters from the comics to created something new so the expectation of it was not high which has helped it has dc fans or fans of the shows don't have preconceived ideas about it.
Preview pics from Ep "Destiny"
Ep 14 "River of Time"
Without spoiling too much a really Ep, the only couple things that spoiled it without giving away anything are a stupid move by a certain character and the usually CW problem with dealing with romance/relationship aside from that it was good.
the ending the ep was good. hopefully the last two eps of season 1 match the standard of eps 13 and 14 otherwise it could spoil what has turned out to be a pretty decent show.