Fort Rozz is orbiting a blue star that is supposed to be deadly to all men, since the radiation destroys Y-chromosomes, but J'onn only masquerades as a man, he is not human at all, he is really a green Martian.
At the end of the episode, Julia is hit by a car. However, when she pushes the car away from her only seconds later, there is no driver in the car.
When Alex gets a text from Maggie, Maggie gives Alex her new address in National City, including a zip code "44333", That is an Ohio zip code, but it is apparent that National City is supposed to take place somewhere on the West Coast, presumably California. Also, later on in the episode, when Alex is writing Maggie's address down on an envelope, the zip code used is "91604", which is a Los Angeles, California zip code.
In Legion of Superheroes, Mon-El mentions to Querl Dox/Brainiac-5, to be careful because of the "precious cargo on-board." This dialogue mentions that the Legion's ship has other Legionnaire's on board in hyper-sleep/stasis while Brainiac-5 piloted the ship for battle against Reign, yet in Fort Rozz, the Legion's ship is used again, to travel to the blue star, with no mention of what has became of the inactive members of the legion.
Whether they are still in hyper-sleep/stasis on board the ship or the inactive members have been taken off the ship so it can be used for missions is unknown.