The characters in the DC shows on The CW, The Flash and Arrow, co-exist in the same universe, allowing for plenty of crossover opportunities.
A mini-crossover between The Flash and Arrow will involve Felicity and other female characters in a “girls night out” event.
Throughout each season, characters from The Flash, Arrow, and Legends of Tomorrow guest star in the other shows.
Aside from participating in the annual crossovers along with most of the cast of Arrow, Felicity was also used as a potential love interest for Barry in the first season of The Flash.