Apparently taking a leaf from Marvel's playbook, DC's upcoming The Flash movie is turning into something of a superhero mega multiverse mashup, with the latest reports suggesting that Grant Gustin will make a cameo in the film. Already boasting appearances by Michael Keaton and Ben Affleck as their respective Batmen - the former of which is obviously going to be huge nostalgia draw for many fans - and Sasha Calle as Supergirl, it now seems that the CW series' Flash will also be dropping in.

While Marvel has frequently had characters dipping in and out of their movies, and more recently have been edging towards their multiverse, DC have already dipped into franchise crossovers in their TV ventures, having seen Ezra Miller, who plays Justice League's Flash, making a cameo in their Arrowverse event, Crisis on Infinite Earths, which also brought together the leads of Legends of Tomorrow, Supergirl, Batwoman and The Flash among others. Thanks in part to Miller's appearance in that series, DC have cleverly paved the way for any number of crossovers between their big screen and small screen characters.

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Speaking to Vanity Fair back in August, movie director Andy Muschietti spoke about DC's multiverse and how it would allow them to bring Keaton's Batman back to the screen for the first time in 30 years.

"This movie is a bit of a hinge in the sense that it presents a story that implies a unified universe where all the cinematic iterations that we've seen before are valid. It's inclusive in the sense that it is saying all that you've seen exists, and everything that you will see exists, in the same unified multiverse."

While we are becoming more accustomed to TV/Cinematic crossovers, having Justice League's Miller appear in the Arrowverse, and now Grant Gustin's Flash appearing in the movie universe, is something that at one time would have been unheard of. As we move further down the rabbit hole of streaming platforms being able to command movie style budgets, and actors willing to walk the line between TV and film, it is becoming harder to see a line between the two.

Only a few years ago, the idea of Stephen King's The Dark Tower being developed to include multiple cinema releases and bridging TV shows was balked at, and ultimately seemed to lead to the stalemate that ruined the movie that did manage to skulk out of the shadows, but if the same prospect was being offered now, it could well have been a different story.

When the DC TV universe connected with its cinematic one, it was not only fans who were surprised by the moment, as Arrow and Legends of Tomorrow producer Marc Guggenheim couldn't quite believe that the cameo had been pulled off. Speaking on Fake Nerd Podcast, he said, "There were certain things that we knew were not touchable and the cinematic universe fell into that category...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 was 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."

With the likes of The Suicide Squad and The Batman already having TV shows in the works, it is not hard to see that what Marvel have done by bringing their cinema stars to the small screen in WandaVision, Falcon and The Winter Soldier and Loki has not been a fluke, and it looks like we can expect much more blurring of lines between the two mediums in future.