The Joker makes a deal with Lex Luthor to kill Superman for 1 Billion dollars.
We notice that Batman is a few blocks away and staring at Clark through binoculars almost immediately after Clark finds the bug on his costume. If Superman usually flies everywhere he goes in costume and we know he had his costume on when he got home ,how did Bruce keep up with him and find the apartment so quickly. It would have taken Bruce at least 5 to 10 minutes to locate and arrive at the bugs signal.
Goof: The episode title contains a typo. It appears on screen as "Worlds's Finest."
The scientist times the WayneLex T7 at 14.8 seconds, but the stopwatch he is holding is clearly pointing to 30 seconds.
Joker: Ceasar Carlini, my old pal! Why, I haven't seen you since... Wait, I've never seen you, have I? You need to get out more.
Batman:: (holding up sliver of kryptonite while Superman buckles) It doesn't take much, does it? The Joker has 20 pounds more where this came from. (throws kryptonite into nearby glass) Thought you might like to know. (Disappears)
Bruce Wayne: (about Superman) How do you contact him?
Lois Lane: Commiting a felony helps.
Superman: (X-Raying through Batman's mask) Bruce Wayne!?
Batman: You peeked.
Superman: (to Batman) I heard you were crazy, I didn't think you were stupid.
Joker: Pay me 1 Billion dollars, and I'll kill Superman!
Lex: What makes you think you can kill Superman when you can't even handle a mere mortal in a Halloween costume?
Joker: There's nothing mere about that mortal!
The Joker: (to Lex) I sense we are kindred spirits, you and I. Although there are differences to be sure, like hair.
This three parter was later released on DVD as The Batman/Superman Movie.
Originally aired as part of The New Batman Superman Adventures in an hour and a half Saturday morning timeslot. Only the first half hour got the traditional TNBSA opening credits, although each half-hour segment had the episode title ("World's Finest Part I," "World's Finest Part II" and "World's Finest Part III").
Superman claiming he had heard Batman was crazy refers back to the pilot episode, "The Last Son of Krypton" when Martha Kent told Clark she didn't want anyone thinking he was like that "nut" in Gotham City.
This marks the first Superman/Batman crossover.
Joker(Admiring the seats inside Luthor's limo):Oooo Rich Corinthian leather
This was a allusion to the 1976 Chrysler Cordoba advertising campaign, featuring celebrity Ricardo Montalban. Who is famous for his line about the rich Corinthian leather in the Cordoba's interior seats. The Joker even imitates Montalban's accent.
The Joker: Oh, you'll be Mr. Clean!
When Joker offers to kill Superman, Luthor says that he (Luthor) can't be connected to it in any way. Characteristically, Joker reassures him while at the same time making a joke about Luther's lack of hair, referring to the burly, bald man on the cleaning liquid bottle.