- Approval of God: Neil Gaiman gave Scott Snyder his blessing when he asked for permission to use Dream of the Endless in the story.
- Development Gag: Numerous Dark Multiverse Batmen in Death Metal were originally developed for Dark Nights Metal but got cut since there wasn't enough room for all of them.
- Dueling Works: With Marvel's Doctor Strange: Damnation.
- Fan Nickname: The Batman Who Laughs was called "Cenobite Batman" before his name was revealed. Also "Laughable Bats" of those fans which found his concept and design to be silly instead of scary or interesting. He has alternately being called Giggles, and in Spanish, El Risitas (the little laughs). There are also nicknames that change "laughs" for "keks", "lols", and "lmaos".
- Promoted Fanboy: Look past accusations of reusing storylines from the man, Scott Snyder is clearly heavily influenced by Grant Morrison's run on Batman. Now Snyder gets to co-write with them on Dark Knights Rising: The Wild Hunt, a book Snyder created as an attempt to dispel any Artist Disillusionment Morrison might have gone through and return them to writing for mainstream comics again.
- Recycled Script: Multiversal threat. Earth sinking into darkness. Evil Counterpart (in this case a bunch of them) working for the Big Bad. A cult/secret society of villains that worship said Big Bad. Batman is trapped in a Lotus-Eater Machine. The story heavily involves the DCU's history, stretching all the way back to the Stone Age and especially involves DC's immortal characters. The bad guys are winning, and the heroes end up feeling more like a resistance than anything. Superman is forced to partake in a journey to outside of the Multiverse to figure out a way to defeat the Big Bad. The story dives into metatextual observations about characters and universes being individual stories. The origin of the Multiverse is explained, and the villain was a crucial part of its backstory, having committed a FaceHeel Turn in a desire to destroy. And finally, this is a Crisis Crossover that also ties into the writer's run on Batman. Is this Dark Nights: Metal or Final Crisis? Tropes Are Not Bad, however, Dark Nights: Metal has enjoyed much more positive reception than Final Crisis, due to a clearer narrative that is much less reliant on the reader having an encyclopedic knowledge of DC's history. Taken further with Morrison themself co-writing a tie-in to the event.
- What Could Have Been: Scott Snyder says he came up with the idea for Metal when thinking about a Hawkman run he wanted to do. Given Snyder's heavy use of noir-style narration and darker, violent stories, it's a shame that run never happened with Katar Hol, who is a space cop. Instead, Metal features Carter Hall, an archaeologist.
- Snyder has said that he had planned for many more Dark Multiverse Batmen but had to cut them from the story. These include a Punisher-style Batman, a Batman that delved into black magic, a Batman that merged with all his villains, one that merged with Gotham City itself and one that was accused of murdering his parents in the alleyway as a child and grew up as a patient in Arkham. This last one was later reused for Batman: Last Knight on Earth and the first one became the Grim Knight, the secondary antagonist of the Batman Who Laughs's titular miniseries. The others were used in the sequel, Dark Nights: Death Metal.
Trivia / Dark Nights: Metal