This is one of the few Batman cartoons that does not have Two-Face in it.
Why do Hawkman and Green Lantern need to get their powers back from the androids? Wouldn't it be smarter for Green Lantern to simply recharge his ring? Hawkman has wings. He might lose his super strength, but he can still use his wings to fly.
Look closely: Much like in "The Batman/Superman Story," despite being near the sun, you cannot see Mercury or Venus. Another point is that the sun is a couple of thousand times smaller than in reality. Also, it is a few million miles too close to Earth.
When J'onn asks Batgirl to set up the code to defeat the Joining, she says "She's still trying to figure out the remote on her TV." This doesn't make much sense because in the past, she has proven to be good with anything technical; in "Attack of the Terrible Trio," she was working on the Bat-computer, in "White Heat" she knew how to use the radiation detector, in "Thunder" she knew how to hack into Zeus' systems, and in "The Apprentice" she knew how to use the tracer device that she planted on Joker. Additionally, she was even shown using a remote for a TV fine in "Batgirl Begins Part Two."
Martian Manhunter: (about his robot double) He's using my invisible power.
Green Arrow: You've got so many, it's hard to keep track.
Batman: Looks like Hugo got his wish.
J'onn: Absorbing all that knowledge has overloaded his cerebral cortex.
Robin: If that's the shortcut to total knowledge - I'll stick with middle school.
Robin: Man, we've got the coolest clubhouse.
Batgirl: Yeah. Junior Justice League, teen division!
Batman: Nice try.
Batgirl: (inputting the code) Hey - how come I know how to do this?
Martian Manhunter: I'm in your mind, relaying the instructions from Strange.
Batgirl: Whoa. We need to talk personal boundaries after this.
Martian Manhunter: Batgirl, I need you to set up the signal! Now!
Batgirl: Me?! But I'm still trying to figure out the remote on my TV!
Batman: I'm patching into the League's satellite to monitor the fight.
Robin: So, what do we do?
Batgirl: Make popcorn?
Hugo Strange's final fate: The Joining gives him the infinite knowledge he desired, however, it was too much for his brain to hold, leaving him catatonic.
"Junior Justice League, teen division" = Young Justice + Teen Titans.
When Batgirl referred to herself and Robin as the teen division of the Justice League, she alluded to the existence of Young Justice, a team of younger superheroes (created in 1998) made of sidekicks and proteges of members of the Justice League. And the 'teen division' designator refers to a similar team of young heroes, the Teen Titans (originally created in 1964).