Maurice LaMarche voices both Mr. Freeze and the Calendar Man in this game. Seeing as this is Julian Day's only voiced appearance in the Arkham games, it makes this trope particularly noteworthy for LaMarche.
Troy Baker portrays both Harvey Dent/Two-Face, and Tim Drake/Robin.
Grey DeLisle plays Vicki Vale and also does Selina Kyle/Catwoman. She would later reprise both roles in Arkham Knight.
Kevin Conroy voices Batman/Bruce Wayne as is standard of him, but also voices Thomas Elliot/Hush, due to Elliot's constructed appearance to make himself look like Bruce Wayne. Like with Grey DeLisle above, Conroy would do both roles again in Knight.
Nolan North voices both The Penguin and Black Mask. North also provides the voices of several randomized inmates. It'll be quite common to hear Penguin berating his Mooks about how much they suck, only to hear a mook voiced by North to reply "You heard Penguin! Let's move!"
Steve Blum returns to voice Killer Croc for a brief cameo appearance in the middle of the game, and also voices Sickle, one of the Abramovici Twins.
Fred Tatasciore also returns from Asylum to voice Bane once more, voices Hammer of the Abramovici Twins, and also plays Solomon Grundy.
As the generator slams Clayface into the Lazarus Pit and explodes, the vial holding the cure is in Batman's left hand, but when he comes to, it's in his right one. Until Arkham Knight confirmed the Joker died, some people speculated that it was intentional, and the Joker took some of the cure and was faking his death. After Knight, though, it's become clear that it was indeed a screw-up.
In the remaster, the damage to the batsuit completely vanishes during the cutscene where Penguin revives Solomon Grundy.
Development Gag: At one point, Batman overhears thugs talking about the rumor that Harley Quinn used to be a man. Harley Quinn was actually motion-captured by a man, and they even released a fake reveal trailer to tease fans about it.
Fake Brit: Starting with this game, the cockney-accented Penguin is played by the American Nolan North in all his appearances throughout the Arkham franchise.
Fake Nationality: Ra's al Ghul is implied to be a middle-eastern man based on his accent. His voice actor, Dee Bradly Baker, is American. Similarly, Talia al Ghul is voiced by the Canadian-American Stana Katic.
Fake Russian: The Abramovici Twins are both voiced by Americans Steve Blum and Fred Tatasciore.
God Never Said That: Many have misquoted or misinterpreted Mark Hamill as saying this game will be the last time he plays The Joker. He clarified that what he meant was he wouldn't continue playing The Joker if he felt that he couldn't top his performance, he wanted to leave on a high note. He has since played the Joker again on multiple occasions, until permanently retiring from the role in early 2023 after Kevin Conroy's passing.
The Other Darrin: Tara Strong replaces Arleen Sorkin as Harley Quinn noteas Sorkin had retired as a voice actor by this point, David Kaye replaces Tom Kane as Commissioner Gordon, and Grey DeLisle replaces Tasia Valenza as Martha Wayne. The latter two are perplexing since, as noted above, Tom and Tasia returned from the first game to reprise the respective roles of Quincy Sharp and Poison Ivy.
Pop-Culture Urban Legends: For a good while, there were several alleged Man-Bat sightings. This has since been thoroughly Jossed; not only does closer inspection reveal them to be just birds flying closer to the camera than normal (making them appear larger), but there's nothing in the game files relating to Man-Bat. Four years later, Arkham Knight would eventually put the final nail in the coffin by revealing that Man-Bat didn't even exist when City took place.
Prop Recycling: The silhouette of Nora Fries in her ice chamber is portrayed with the same character model as the kidnapped hospital intern from under Wonder Tower, albeit without eyes.
Role Reprise: In the French dub, in addition to the same role reprises featured in Batman: Arkham Asylum, a few more voice actors from previous adaptations reprise their roles here:
Show Accuracy/Toy Accuracy: The Penguin figure released by McFarlane Toys in 2022 depicts him with his top hat, despite him never wearing it in the game.
Viral Marketing: Starting in early October 2011, major YouTubeTheGameStation affiliates Husky Starcraft, OMFGcata, TotalHalibut, and the Yogscast left mysterious Riddler question marks in their daily videos: Each one linked to an unlisted YouTube video part of a four-part audio involving Professor Strange and Two-Face that promoted the game and its Facebook page.
Voices in One Room: Kevin Conroy and Mark Hamill recorded their lines together for the cutscenes where Batman and the Joker interact.
In an interview, director Sefton Hill said they wanted to include a reference to the infamous Bat-Shark Repellent Spray from the Adam West seriesnote Reportedly, when confronted by "Tiny" in the Iceberg Lounge, Batman would break out the repellent... then open it up to reveal a set of brass knuckles, but ended up nixing it because they felt it was a Level Breaker. There's still a subtle reference; if you get killed by the shark, one of the possible hints reminds you to remember Batman's shark repellent: a flurry of blows to drive it off. In one room, you can listen to the Riddler mutter about ways to take down Batman, and ponders taking Penguin's shark, only to say that there are "too many variables", and that Batman likely has some sort of "shark contingency".
Arkham City was released the same day as Batman: Year One and shares a lot of the same voice talent: Grey DeLisle (Catwoman, Vicki Vale, Stacy Baker, Martha Wayne) is Barbara Eileen-Gordon and Vicki Vale, Steve Blum (Killer Croc and Sickle) is Stan, Fred Tatasciore (Bane, Solomon Grundy and Mr. Hammer) is Arnold Flass and Johnny Vitti, and Danny Jacobs (Victor Zsasz) is Flass's lawyer.
to tease fans about it.