-Crisis on Infinite Earths will be a 5-part story (Arrow, The Flash, Legends of Tomorrow, Supergirl, and Batwoman)
-3 parts will air in December and the second 2 parts will air in early 2020
-Legends of Tomorrow season 5 will arrive at mid-season (Jan, 2020) and will be one of the two crisis episodes (don't know what the other show will be)
-Arrow & Flash finales included hints/lead in into COIE
-[Spoiler (click to open)]source: me since i watched both eps lol
On Arrow the Monitor comes to collect on the deal he struck with Oliver in Elseworlds to save Barry & Kara. He takes Oliver away from Felicity and their newborn daughter, Mia, on a trek across the multiverse to begin an attempt to fight the incoming Crisis.
Over on Flash in Barry's faceoff with Eobard, the villain drops a cheeky "see you at our next crisis" before Barry lets him go to try and save Nora. And at the end of the episode that infamous "Flash Disappears in Crisis" newspaper we've seen since the pilot's date changes from 2024 to 2019 because Nora's shenanigans since the end of season 4 have moved up the timeline 5 years.
-Supergirl's finale this coming Sunday will also contain a crossover easter egg
-batwoman will premiere and lead in supergirl this fall
-the flash stays in its tuesday slot followed by arrow which will return for its finale season