The CW's DC television crossover event "Crisis on Infinite Earths" was packed to the brim with cameos, reaching well beyond the Arrowverse to showcase countless faces from DC Comics' on-screen history. Arguably the most shocking cameo of them all, however, was when DC Extended Universe star Ezra Miller reprised his role as Barry Allen/the Flash and came face-to-face with Grant Gustin's TV version of the character. Arrowverse architect Marc Guggenheim has now opened up about how this seemingly impossible meeting became a reality.
Guggenheim discussed the matter during an appearance on the Fake Nerd Podcast. "There were certain things that we knew were not touchable and the cinematic universe -- before that call -- fell into that category," he said. "The nice thing about doing something for years is you're there for all the changes. You're there for the personnel changes, and you're there for the philosophical changes and the changes in policy, and this just happened to be one of those situations where people changed their minds. I was so glad that they did, even though the change of mind did come after we were wrapped on the whole crossover. So it came very late, but as they say, better late than never."
Guggenheim explains that he and his team were "thrilled. I did feel like the cinematic universe was the one that got away. If you were to ask me -- short of bringing Christopher Reeve back to life -- what would you most want to do, I would have said include the cinematic universe, and I still can't believe that we were able to that. The funny thing is, once we got the approval, it came together almost easier than any other cameo. I mean, certainly, there were other cameos that were a lot harder to pull off, that required a lot more scheduling creativity or financial creativity or logistical creativity, you name it! This sort of all came together really nice." He says getting Miller's cameo scene done was as simple as "series of phone calls and some time at the keyboard."
Then, of course, there is the topic of how exactly the Arrowverse team managed to keep such a big guest appearance under wraps. "There was a lot of back and forth about whether or not we were going to keep it secret," Guggenheim shared. "I was amazed that it was able to surprise people, because we live in a world where it's really, really, really hard to -- you know, there's cameras everywhere. There's leaks everywhere, and it's really hard to genuinely surprise the audience... No one knew! Nobody knew. And in large part, it was because once the decision -- again, way above my head -- was made to keep it a secret, everyone understood the importance of keeping it a secret. It was like, 'We're out of our TV bubble here.' This is now involving theatrical! This is involving the upper echelon of Warner Bros.! If the powers that be have decided that this is to be a surprise, then we have got to move heaven and Earth to make sure it's a surprise.
"I think most people -- the people who care -- knew that the event was wrapped," he continued, "So, if Ezra Miller were to show up in the Vancouver airport, where a lot of paparazzi hang out, several months later, which is what happened, no one was going to bat an eye. As it turns out, no one even got pictures of him walking through the Vancouver airport, which I have to say was a small miracle."
Miller made his debut as the DCEU's Barry Allen in 2016's Batman v Superman: Dawn of Justice, subsequently reprising his role for a cameo appearance in Suicide Squad and a leading role in 2017's Justice League. His cameo in "Crisis" marked his first appearances as the character since the latter film. His long-gesting Flash solo film is currently scheduled to arrive in July of 2022. Gustin, meanwhile, has starred as the Arrowverse's Barry Allen since debuting as the character in a 2013 episode of Arrow, with his own spinoff arriving one year later. This past January, The CW renewed The Flash for Season 7.