Corinne Bohrer reprises her role as Zoey Clark / Prank from Trial of the Trickster (1991). After Amanda Pays (Dr. Tina McGee), Mark Hamill (James Jesse / The Trickster), Vito D'Ambrosio (Anthony Bellows) and Alex Désert (Julio Mendez), she is the fifth actor to play the same character in both The Flash (1990) and The Flash (2014). John Wesley Shipp also appeared in both series, playing the title character Barry Allen in the former and his father Henry Allen (and his Earth Three doppelgänger Jay Garrick) in the latter.
After seeing his fathers writing of "Henry Allen was here" on the wall of the jail cell, Barry writes "So was Barry". A possible nod to "Brooks was here"; "So was Red" from The Shawshank Redemption (1994) When Barry met Axel and said that he was innocent, Axel replied that everyone there was innocent. Another possible reference to the scene from the movie where Red met Andy.
Ralph addresses himself to the bomber as your "friendly neighborhood superhero" a reference to Marvel superhero Spider-Man He continues that phrase with "Mister..." but stops there, referencing Mister Fantastic, a Marvel superhero with similar powers. It's a parallel to a simliar situation back in S1 episode 8 Flash vs. Arrow (2014) when Iris asks the Flash what his real name was and the reply was Ralph coincidentally Elongated Man's civilian first name.
During his closing scene with Cisco, Ralph questions the need of a mask with his costume. In the comics Elongated Man came to eschew wearing a mask, and was DC's first hero whose secret identity is voluntarily known to the public.
In DC comics, Big Sir was a Flash villain whose real name was Dufus P. Ratchet.