The Flash Season 2: 28 Easter Eggs & References You Might've Missed
10. Opal City
When Jesse decides to leave Central City behind to explore Earth-1, she does so on a bus headed for Opal City, bringing into play another DC Comics city (it had been mentioned previously on Arrow, but this is the first shout-out it's received on The Flash).
Opal City is most notable as the home of Starman, moniker adopted by several superheroes. The Elongated Man is another notable resident, as is the Shade, a character who has long been tipped for an appearance in the Arrowverse. Opal City also exists on Supergirl's Earth, as it's where Cat Grant's son lives.
Also of note here is the bus Jesse leaves on, which is operated by Midway, another reference to that city.