It is so stupid that Batman isn't allowed on the TV shows, yet they have Superman show up in Supergirl.
Many Bat-easter eggs, Bruce and Batman have left Gotham years ago. Oliver thinks Batman is a myth and that Arrow is the original vigilante. Supergirl's Earth Bruce Wayne is frenemies with her cousin. Also a subtle nod to Adam West Batman when Kara held the bust of the bard. The same one that Adam would open to hit the switch to the batpoles....
Plenty of freaky-friday, quantum leap jokes.
Amazo android went on a rampage and copied all their powers, even the power less Green Arrow....which should not have happened.
Earth-90 is the 90's Flash Earth.
Mildly amusing seeing Oliver and Barry switched and emulating each other.
Jonathan Crane fear gas...creates images of Malcolm and Wells-RF which causes an completely improbable fight with Oliver and Barry......surely the super speedster would be an auto-win. Also the Wells-RF was a hallucination from the fear gas, not the actual Wells-RF
Supergirl makes friends with Batwoman and of course they know who each other is....
Olicity reunites and then Flash-90 finally arrives and tells them of the Monitor, the book, and that it is all a test for an upcoming Crisis....
also that on Earth-90, John Diggle is Green Lantern
They confront the Monitor and Earth-90 Flash is rather easily blinked out of existence.
Monitor is testing universes to find one strong enough to stop the one that is coming that is stronger then the Monitor.
Reality gets warped so that Oliver and Barry are now criminals and have no powers.
Thye attempt to flee and are intercepted first by Diaz who is now a cop....then a black costumed Superman....
Monitor then has a chat with them about destiny while Supergirl is locked up in the tunnel at revised Star Labs
They find the now evil Cisco and get to Earth 38 to get the real Superman to deal with the dark fake.
Superman and co. arrive in time to save Kara and Earth 1 Alex from Dark Superman. Superman says "nice suit....Dr may I have a word?" and the fight is on.
Pointless fight and of course Dark Superman appears to be stronger.
Clark uses the book to start restoring things but Dark Superman takes the book and flees
Barry comes up with the plan to alter Earth's centrifugal force to slow down time so they can get the book back. Superman warns the book reveals they will die doing this.
Oliver confronts the Monitor and changes the destiny of them.
Okay so Mach 7 is enough to affect the spin of the Earth and slow down time.....
Seriously we just had to revisit the Superman 1 concept of spinning the Earth to affect time.....? Ugh
Entertaining story until the Earth spin schtick.....
Superman and Lois go away to have their baby.....he also does the old crush coal into diamond trick as part of the marriage proposal....
It all ends with Barry and Oliver at a bar and Batwoman calls Oliver to warn him that Deegan has made a new friend.....the Psycho Pirate, who teases the impending Crisis on Infinite Earths.
Monitor did state that Kara and Barry would die, but I suspect the change he made for this story means they die in Crisis.
Not pleased with how Earth-90 Flash was so quickly dissed and dismissed, not pleased at all.
Also this is where all three shows should stop, not just for the holiday, but just stop for the whole season. Then come back for the Crisis and let that be the finale for the CW/Arrowverse.
It is time to stop this trainwreck before more cars pile up.