3) Arrow’s Advice – The Flash
Arrow has now got to be one of the most successful series in history in terms of starting a wide connected universe of shows. Before it got to that stage, though, it had to help its first spinoff The Flash stand on its own two feet. How could that be done? By having Stephen Amell’s Arrow appear in the show’s pilot episode.
Having just received his speed powers, Barry Allen turns to his old friend Oliver Queen for help. Oliver inspires Barry to be something more than a vigilante; a hero who can save the helpless “in a flash.” The pair then admire each other’s “cool” ways of disappearing.
It’s a low-key scene in the wider world of superhero crossovers, but this first meeting of the characters in their superhero identities meant a lot at the time. The Arrowverse had just begun – but it would soon expand very quickly.