Concerning the Flash, this episode seems at odds with the immediately preceding one, "The Ties That Bind." There he was griping about how he's dismissed as the teen sidekick. Here's he's still one of the core seven, which seem to be an Inner Council for the League as a whole. It's unlikely what he did in "Ties" improved his status, so why the sudden change?
Hawkgirl's status is unclear within the League position-wise, but there is one mismatch: she's in the initial "head honchos" conference at the beginning when they're discussing Cadmus, but at the end she's not in the tribunal that is interrogating Doomsday (the empty chair is presumably Batman's). Shouldn't she be at both?
There are no other Leaguers on the Watchtower or on other parts of the globe that can intercept the missile in time...but why can't Wonder Woman and the Flash? She's super-strong, super-fast, and has a lasso, he can run at super-speed and generate tornadoes and water spouts, and the missile's heading right for them.
In the hangar in the long shot, Wildcat is in the lead, Hourman is in the middle and to Wildcat's right, and the much darker, shadowy Obsidian is bringing up the rear to Wildcat's left. But in the close shot when Batman comes charging in, Obsidian and Hourman instantaneously swap left-for-right and the two of them are walking even.
When Doomsday initially charges towards Superman, he runs across the lava at Superman's level. But as we saw when Superman burst into the chamber, the floor of the chamber is about 8-10' below the level of the lava, which flooded the chamber when Superman burst in. Superman only appears level with the lava at this point because the rock-pedestal he was standing on was about 10' tall. Doomsday should sink into the lava, which is about 8' deep.
How did Doomsday know where Superman was? He had no access to Cadmus research, no indication he has the smarts to access their security systems from the pod, and there's no reason the pod would have a built-in Superman-tracking unit.
When Doomsday busts out of the lab, bursts of energy hit him from his left, and he looks left. Then they cut to a shot of the guards in a corridor even though the lab door should be to Doomsday's left. Then Doomsday walks straight ahead and attacks the guards.
In the medlab, Bruce Wayne's eyes are brown. In "The Once and Future Thing: Weird Western Tales", they're blue.
In one scene, Amanda mentions seven Justice Lords, but there were only six. The Flash was never a member of the Justice Lords.
Superman: You don't owe anything to them. They manipulated you and then tried to kill you.
Doomsday: So I keep hearing.
Superman: I know who you are. But I'm not the one who hurt you.
Doomsday: Superman is Superman. And I will kill you.
Doomsday: It's what I am--I don't care why.
Doomsday: Superman. I'm here to kill you. Is this a bad time?
Waller: Milo! I'll have his hide for this.
Security Guard: Doomsday beat you to it, ma'am.
Waller: Dr. Milo - I'm not known for my sense of humor, but I know a sick joke when I see one.
Batman: Call off the missile.
Waller: How did you get this number?!?
Batman: The missile heading for San Baquero. If anyone dies on that island today, I'm coming for you.
Batman: I've got the Question looking into it, and...
Flash: Not that kook!
Batman: I admit, he's wound a bit too tightly...
Flash: (The Justice Lords) went overboard because their Flash died. So as long as you all focus on keeping me alive, that'll never happen here.
J'onn: Lets put a pin in that theory to explore another time.
Batman: What would stop you from doing what that Superman did?
Superman: There's always that kryptonite you carry around.
Batman: You don't get to joke! Not today! I just took a bullet for you.
Batman: Sent him off to the Phantom Zone, didn't you?
Superman: He left us no choice.
Batman: Spoken like a true Justice Lord.
The "Langstrom research" that Dr. Milo refers to is tied to Batman: The Animated Series and the episode "On Leather Wings." Dr. Kirk Langstrom was a scientist who studied bats and developed a serum that turned human beings into man-bats.
The armor that Waller and Tala discuss is presumably the Annihilator battle-armor that Hephaestus built for Ares in the episode "Hawk and Dove". Tala and the Annihilator (and Lord Hades) can be seen in the end-of-episode previews.
Other heroes that appear without dialogue: Hawkgirl, Green Lantern, Hawk, Vixen, Fire, Ice, Black Canary, Booster Gold, Vibe, Wildcat, Hourman, Obsidian, and Shining Knight.
C.C.H. Pounder, Michael Jai White, J.K. Simmons, and Robert Foxworth reprise their prior roles of Amanda Waller, Doomsday, General Eiling, and Professor Hamilton, respectively. Armin Shimerman takes on the role of Dr. Milo, who was previously played in Batman: The Animated Series by Treat Williams.
Previews at the end of this episode on its original airing are from the upcoming episode "Double Date" and at least one other unidentified (as of 2/19) episode.