During the commentary, when the camera focuses on Hawkgirl, there is a rather large bush behind her. When they zoom in, it's missing.
When the League is carrying Superman's casket to the place of burial, between front and rear shots, Green Lantern's "robe" disappears and reappears.
Further on Superman as Clark Kent - who invited his adoptive Earth parents? Superman's funeral would be a world-class event, with only limited attendance inside the chapel during the actual service. Not only superheroes but dignitaries, Presidents, etc., from across the world would be present and expect to be among those given the limited seating. Short of revealing that they're Clark's adopted parents, how the heck would the Kents get seated near the front row? And even if Bruce Wayne pulled some strings, wouldn't that raise suspicions that they had some connection to Superman? That, along with Clark's absence (see above) would seem to permanently blow Superman's secret ID.
No one noticed that Clark Kent didn't show up for Superman's funeral? Has the whole world just been humoring him about his "secret identity" all this time?
Why are the police unable to do anything? We've seen in the past that Metropolis has a Special Crimes division headed by Maggie Sawyer (who we see later at Superman's funeral), with super-powered weapons and all. But they're curiously absent here.
Martian Manhunter: Though we gather here today, bound together in sorrow and loss, we share a precious gift. We are all of us privileged to live a life that has been touched by Superman. The Man of Steel possessed many extraordinary gifts, and he shared them with us freely. None of these gifts were more remarkable than his ability to discern what needed to be done and in his unfailing courage in doing it, whatever the personal cost. Let us all strive to accept his gift and pass it along as an ongoing tribute to Kal-El of Krypton, the immigrant from the stars who taught us all how to be heroes.
Flash: I used to be able to goof around so much because I knew Superman had my back. Now all I've got is his example. And that's gonna have to be enough.
Lobo: Brave talk for a dead man.
Kalibak: I'm not dead yet.
Lobo: You're right – my watch is about 10 seconds fast.
Lobo: Finders keepers on any bounties, right?
Hawkgirl: You need to be quiet now.
Kalibak: This looks like a job for Superman . . . but I don't think he's coming.
Wonder Woman: You're no Superman.
Lobo: The ladies say different.
Flash: Yeah, Aquaman could definitely pick up Batman's slack in the pompous jerk department.
Toyman: What are you gonna do to me?
Wonder Woman: I'm gonna punch a hole in your head.
Flash: We don't do that to our enemies.
Wonder Woman: Speak for yourself.
Flash: I'm trying to speak for Superman.
Kalibak: I just flattened Wonder Woman. You really think you can beat me?
Batman: I'm not trying to beat you – I'm trying to stall you.
Kalibak: Stall me? For what? (Superman arrives) Uhhhh...
Lex Luthor: Believe it or not, I'm going to miss (Superman) too.
Originally Captain Marvel was to take Superman's place (rather then Lobo), But it turned out the rights weren't available and they went with Lobo.
When discussing League membership, Wonder Woman asks Batman if he wants to become a full-time member. This confirms the comment made by Barda in Batman Beyond about the original Batman never making it past part-timer ("The Call, Part 2").
This episode features Kal-El's second funeral in the WB Animated DC Universe. The first occurred in the Superman: The Animated Series episode "The Late Mr. Kent", where Clark Kent was presumed dead in a car accident.
Whereas Wonder Woman's regular costume features the classic "WW" logo, her formal attire (that she wears to the funeral) appears to sport the logo that appeared on Lynda Carter's WW costume in the late 70s.
Other heroes suggested for membership included Aquaman, Metamorpho, and Supergirl.
Present with no dialogue: Hippolyta; Green Lantern's Tomar Re, Arisia, Katma Tui, Kilowog, Larvox, and an unidentified brown-skinned Lantern (apparently Kyle Rayner); Tim Drake; Alfred; Maggie Sawyer; Orion; Bibbo Bibowski the Sailor (who Brad Garrett also voiced in Superman: The Animated Series); Aquaman, Mera, Dr. Fate, Inza, Martha and Jonathan Kent, Lana Lane, Supergirl, Jimmy Olsen, Perry White, and Barbara Gordon.
Other villains seen: Copperhead, Star Sapphire, Volcana, Livewire, Deadshot. None of them except Deadshot and Livewire have dialogue and those two aren't voice-credited. Livewire clearly isn't Lori Petty, who played her in Superman: The Animated Series).
The entire League appears in this episode.
Dana Delany, Efrem Zimbalist Jr., Michael Dorn, Clancy Brown, and Jason Marsden reprise their roles of Lois Lane, Kalibak, Lex Luthor, and Snapper Carr, respectively. Brad Garrett reprises his role of Lobo from the Superman: The Animated Series episode "The Main Man". Corey Burton takes on the roles of Weather Wizard, Metallo, and Toyman - none of which he played in the original Superman: The Animated Series. Burton did play Brainiac, who you think would want some Superman revengin', but apparently he doesn't hang out with mere human amateurs.
When Cartoon Network premiered this episode, they aired the two episodes back-to-back, without inserting closing credits at the end of part one or opening credits/recap at the beginning of part 2. They still listed the title and writer/director credits, though.
Kalibak: This looks like a job for Superman...but I don't think he's coming.
An ongoing line in the old Superman series.
Batman: Perhaps you should get a strap for that?
Said as he disarms yet another villain wielding a handheld power device - seems to be becoming a habit as he references previous episodes such as "Injustice for All (1)."
Green Lantern: Watch out for Iron Giant!
Referencing the animated movie. This episode premiered on Thanksgiving weekend only a few hours after the annual Cartoon Network marathon of the movie. And Iron Giant itself makes several references to Superman, the focus character of this two-parter.
Batman: What did you always call it, Clark... the neverending battle...
Referencing the introductory monologue to the 1951 - 1957 The Adventures of Superman television show starring George Reeves: Faster than a speeding bullet. More powerful than a locomotive. Able to leap tall buildings in a single bound. Look! Up in the sky. It's a bird. It's a plane. It's Superman! Yes, it's Superman - strange visitor from another planet who came to Earth with powers and abilities far beyond those of mortal men. Superman - who can change the course of mighty rivers, bend steel in his bare hands, and who disguised as Clark Kent, mild-mannered reporter for a great metropolitan newspaper, fights a neverending battle for Truth, Justice, and the American Way.