We were series wrapped on Arrow, and we were wrapped on the whole crossover. We were in post and some episodes were locked, and some were soft-locked. I got a phone call from [Warner Bros. boss] Peter Roth saying, “I know you’re locked, but can you put Ezra into the crossover?” And I said, “Yes.” And he said, “How, you’re series wrapped? And you’re wrapped on the crossover.” And I said, “Yeah, I know, but if you’re telling me Ezra Miller can be in the crossover, I can make it happen.

He then went on to say that they waited for Gustin's approval before moving on with the cameo and that both Gustin and Miller were thrilled to do it. The last-minute nature of the scene means Crisis on Infinite Earths was very close to not connecting to the DCEU and that it was only through luck and everyone's enthusiasm that it was able to come together.

Considering the popularity of both versions of The Flash, it's no surprise that Miller's cameo has already become one of the highlights of Crisis on Infinite Earths, if not the entirety of the Arrowverse. Fans were thrilled to see Miller alongside Gustin, even if it was for a short scene. What's even more remarkable is how everyone managed to keep it a secret. In this day and age, spoilers appear on the Internet with such ease that nothing is truly surprising anymore. Luckily, DCEU Barry's appearance in Crisis was able to remain a genuine surprise to the amazement of fans everywhere.

More: Arrowverse's New Multiverse Revealed: Which Shows Are On What Earths

Source: Variety