There are occasional mentions of Yagiri Pharmaceuticals being at risk of being bought out by an American company called Nebula — The same Nebula that constructed the Flying Pussyfoot in the 1930s.
There are also an instance of a clip from Baccano (specifically the fight between Ladd and the Rail Tracer atop a train) playing on a big-screen TV on the side of a building, and again, in the background of one shot was a poster of the Rail Tracer. Both of these instances cause a slight contradiction to the theory that both series are in the same continuity, since Baccano appears to be a TV show or movie in the Durarara era. However, given the existence of Isaac and Miria and Nebula, it could just be a non-fictional movie. But who really knows?
Ennis from Baccano again shows up on a big screen in the background during the second OVA/episode 25.
And for a brief yet hilarious example, click here and close your eyes. Now wonder why the hell Germany is in Durarara and what he's on.
Saki Fujita as Ruri Hijiribe, even if it is a brief cameo.
Mika Harima, in English, is voiced by Carrie Savage- the same voice actor as provided the voice of Lua! It's especially worthy of note in that Carrie Savage is one of the only English voice actors to appear in both Baccano! and Durarara!!, since they're dubbed by different companies (even Isaac and Miria were outfitted with new voice-actors for Durarara!!).
Any time someone logs on to the Dollars web site the password is Baccano!
Episode 1 : A clip of Jacuzzi from Baccano! appears on a Jumbotron; Walker is carrying a cardboard cutout of Holo.
Episode 3 :
"They're pipiru piru piru angels who fly in the sky while showing their underwear to everyone below them!" Also, pictures of the main characters from Baccano! appear in the background, and Walker is carrying a volume of Yozakura Quartet (Suzuhito Yasuda did the character designs for Durarara!! as well). Also: Flame Haze.
Shizuo also gets his face covered in blood lending him some semblance to the Rail Tracer.
When Mikado and Anri flee the Shizuo/Izaya showdown, the way the camera focuses on them Holding Hands and the way Anri ends up half-dragging Mikado bears a strong resemblance to Nice and Jacuzzi in the Baccano! OP.
Episode 6 :
Looking very closely at Kyohei logging into the Dollars website shows that the password is "baccano". Celty watches an alien autopsy show featuring a Suspiciously Similar Song version of The X-Files theme. Walker and Erika also pull out Bludgeoning Angel Dokurochan and Ladies Versus Butlers! novels at one point ("Pick a novel, we'll torture you according to its plot!") and the episode ends on a shot that includes a Hell Girl and Baccano billboard.
One of the various silly claims Teen Idol Kasuka Heiwajima's manager makes about him is that he's a thousand-year-old vampire. Yes, Shizuo's brother is the Gackt of the Durarara universe.
Episode 18 : Yet more Baccano! clips are shown on a tv screen in one scene.
Episode 19: A poster of Chane Laforet from Baccano! can be seen in the background about halfway in.
Episode 20: The gang wars are illustrated using a Taiga figure, a Holo figure, and a Shana figure. There's also a Axis Powers Hetalia gashapon machine in the background, a Hiiro Yuki art book, as well as a clip from Black Butler II on a Jumbotron.
And apparently Lady Gaga is part of Yellow Scarves... [1]
From volume 4: "Tsun tsun dere tsun dere tsun tsun...Kids sing it around the commercial street of Sakurashinmachi." Evidently, Kida reads Yozakura Quartet.
In the first volume of the manga there is a Grellevator.
In the manga, Erika and Walker use a Black Butler} manga as inspiration for their torture. This is most likely because both mangas are being published by a magazine under Square Enix.
Spell My Name with an S: Invoked in Episode 6 by Togusa, who corrects the semi-conscious goon when he calls the group "Dollar".
The fansubbers sometimes subtitle the title as "Dullalalah", which is probably the intended translation seeing as the show is about a Dullahan. Artwork is often emblazoned with "DRRR", but fans tend to take it as a quicker way to refer to the series, and not its actual title proper.
Technically, DRRR!!would be the proper title, given that Narita decided the title the last minute after hearing someone flip through the pages of a book. Since symbols (letters) are made out of sounds in Japan, it would be デュラララ (lit. durarara). In the west, however, it should be romanized as drr[rrr]. It's even written as such in the second opening credits where all of the names are spelled in English. Durarara, however, is decidedly catchier and easier to say.
There's also the Dullahan herself, over whom official materials are totally inconsistent. "Certy" appears late in the novels, she herself uses "Selty" on a computer in the anime's fourth episode, and Shinra has her as "Celty" in his cell phone address book in the sixth episode.
The new opening now gives us the "correct" way to spell the characters names in English.
