Mar Novu's experiment goes wrong sending him to the anti-universe where he unleashes his counterpart. The Paragons travel here to do battle with the Anti-Monitor and recreate reality in episode 8x08 “Crisis on Infinite Earths: Part Four”.
Kara and Mon-El find themselves trapped on Slaver's Moon after Mon-El ignores Kara's orders and follows her through the portal in episode 2x09 “Supergirl Lives”.
M'yrnn gives J'onn one final memory before shapeshifting into the Earth to stop the destruction in episode 3x23 “Battles Lost and Won”. J'onn returns to the spot where his father gave his life and is confronted by Manchester who has recovered a powerful Martian staff in episode 4x15 “O Brother, Where Art Thou?”.
Suzie heads into work and that evening she is pulled outside by the Mage's goons in episode 2x01 “Space Rabbit”. Suzie returns to the quarry to recover her son's cell phone and she has another encounter with the Mage in episode 2x03 “Two Broken Fingers”. Tina and Farah head to the quarry looking for Sheriff Hobbs but are ambushed by the Mage in episode 2x08 “Little Guy, Black Hair”.
Farah and Tina wake up and come up with a plan to rescue Hobbs.
Farah, Tina, and Hobbs try to get themselves to a hospital after being shot.
Flynn and Jesse James rest their horses near the edge of native land and spot the posse following them. When Bass Reeves and the team arrives they find all of the native guards murdered in episode 1x12 “The Murder of Jesse James”.
Jason drives Billy up to the mine so he can dig for his treasures and they end up encountering three other misfits and discovering something beneath the ground.
Most of the survivors from the Enterprise are kept captive at Krall's camp where Jaylah and Kirk lead a daring rescue to save the crew.