Cisco's middle name is revealed to be Baracus, a reference to the character B.A. Baracus from the television series The A-Team. Ralph also says "I love it when a plan comes together", John "Hannibal" Smith's catchphrase from the series.
According to Josh, all of Cisco's other living doppelgangers are meek "pencil pushers" without Earth-1 Cisco's courage. Either he didn't know about Reverb, or ignores that version of Cisco due to Reverb being dead.
In DC comics, there are several characters named or nicknamed "Echo", but this version resembles a Legion of Superheroes villain named Echo, who has vibe powers.
When Wells calculates the oxygen level in the tunnel, the way he uses the handheld device is very similar to Quantum Leap's Al Calavicci's use of his handlink to Ziggy, including hitting the side of the device and the sound effects it makes.
This episode is similar to the S4 episode Enter Flashtime (2018) and the S5 episode King Shark vs. Gorilla Grodd (2019) , as the episodes start off in a predicament then go backward in time while explaining the events that eventually lead up to the original predicament.