Spoilers: DC's Arrowverse crossover event "Crisis on Infinite Earths" has come to an end, before it did, we got a final slew of DC multiverse cameos and surprises. The biggest of those surprises was no doubt the scene where Arrowverse Flash (actor Grant Gustin) bumped into movie Flash (Ezra Miller) during a crucial mission within the Speed Force. The Flash-on-Flash meet-up was a major thrill for fans, as it connected the Arrowverse with its DC Extended Universe cousin for the first time. Now that we've seen a DC movie actor show up in the DC TV Universe, there's been one major question on fans' minds: will we see the inverse occur?
That's is to say: Will we now see Flash TV star Grant Gustin show up The Flash movie or some other DC Films project?
Ezra Miller's Flash has already racked up two mysterious cameos that need full explanation: the first was his time-traveling run from Darkseid's "Knightmare" future earth to the make contact with Ben Affleck's Bruce Wayne in Batman v Superman - now we have this "Crisis" appearance that arguably also needs greater context and explanation.
The fact that Zack Snyder's vision for the Justice League movie saga is now dead means we may never get the explanation of that Batman v Superman scene, but Ezra Miller's "Crisis" cameo was no mere throwaway moment. The scene between the two Barry Allen's hints that Miller's Flash was in the middle of something important when he made contact with Gustin's Flash; more to the point, Miller's Flash actually has no idea about "The Flash" codename until Gustin's Flash gives him the idea for it. Finally, there's the mention that Miller's Flash told Vic Stone / Cyborg that breaching dimensions through the Speed Force was possible, and the hint that Miller's Flash has no idea he's arrived avoided the end of the entire multiverse.
All those clues may point to larger details of the upcoming Flash movie's story - including the question of its timeline, as this "Crisis" version of Miller's Flash already knows his Justice League teammate Cyborg, but doesn't seem to have "The Flash" codename yet? However, the Speed Force sequence in "Crisis" was meant to represent key moments of connection between characters, which suggests Grant Gustin's cameo in The Flash movie could be pivotal.
Even Gustin's appearance in a DC Films project is just used as a fun bit of fan service, there have been enough DC fans clamoring for him to get such an opportunity, for so long, that it would be a major win.
Upcoming DC movies include Birds of Prey (and the Fantabulous Emancipation of One Harley Quinn) on February 7th, Wonder Woman 1984 on June 5th, The Batman on June 25, 2021, The Suicide Squad on August 6, 2021, Black Adam on December 22, 2021, Shazam! 2 on April 1, 2022, The Flash on July 1, 2022, and Aquaman 2 on December 16, 2022.