Normally, that wouldn't matter at all, especially for someone as creative as Morrison, someone more than capable of inventing punchy villains to fill Two-Face's shoes. But in an unexpected move, Morrison marches out a troop of mute and/or brainless baddies: Officer Muller who speaks exactly
Page 2: A million years ago, Commissioner Vane replaced Jim Gordon in Commisioner Gordon Walks a Beat.
In that story, Vane declares that Gotham no longer needs the help of Batman and Robin and even smashes the bat signal with an axe, perhaps the first appearance of this recurring image.
Anyway, there's obviously more to it than just that. It turns out the incompetent mayor and his son were blackmailed by mobsters Smiley and Gomer into giving Gordon's chair to the stooge Vane and severing all ties with the Batman. Interestingly, Smiley and Gomer both love gambling (hmmm, like who else?), and foolishly bet their leverage on the mayor against Batman performing some silly 1950's stunt. Of course Batman pulls it off and Gordon is reinstated as commissioner before the 11-page tale concludes. Suddenly humble, Vane walks away spotless from the whole ordeal, regaining his old position as chief inspector, and now probably spends his days forgetting himself somewhere in Morrison's Limbo.
Page 2: The demonic Third Man, escaped from Batman's nightmares and apocalyptic visions in 665 and 666 respectively
Page 4: The title Space Medicine is borrowed from a line in Batman 156, Robin Dies at Dawn (more on this in next issue's annotations)
Page 6: Third mention of Gotham Noir, the first in 655 and the second in 663. Ed Brubaker wrote an Elseworlds GN called Gotham Noir, but since it's not three hundred years old and not written by Morrison, I doubt he's referencing it.
Page 8: Farelli hassled Batman and some hookers in 664 and 665. He apparently leashes the Three Ghosts, but obviously it's not working out too well since all three of them managed to snap free. Also, in case you're wondering, Farelli does NOT appear in Detective 121.
Page 10: Jezebel "wants to do everything." Mayhew expressed similar sentiments in Batman 669. He had to commit murder because he had already done everything else.
Page 13: Like Farelli, officers Muller, Branca, and Lane the Third Man do not appear in Gordon Walks a Beat.
Page 16: The bat signal shatters and its image becomes distorted, just as in the image above. Symbolic?
Page 17: Gomer and Smiley may have been early members of the Black Glove who grabbed control of the police department during the Vane administration, allowing Dr. Hurt to conduct his perverse experiments unhindered.
Page 18: Batman imagines the Third Man as a monster he previously hallucinated in Batman 156.
Page 20: Recreation of Frank Miller's bat-smashing-window scene from Year One, but this time with a different color scheme. Red and black. Like a bat. In a dream. In a window.