("Suicide Squad."Clay Enos/Warner Bros)

Warning: spoilers for "Suicide Squad" ahead.

"Suicide Squad" is the latest DC Comics release from Warner Bros., and as with its previous title, "Batman v Superman: Dawn of Justice," there are elements to the story that tease the massive convergence of superheroes coming in "Justice League."

For "Squad" it's the blink-and-you'll-miss-it appearance of Justice League member The Flash (Ezra Miller) when he captures Captain Boomerang (Jai Courtney) in assisting Amanda Waller (Viola Davis) to form the Suicide Squad.

It turns out, however, that the sequence came together long after principal photography wrapped. The way Courtney tells it, there was no other actor with him on set when he filmed his portion of the scene.

"I didn't f------ know that was happening when we were filming," Courtney told Business Insider of The Flash appearance. "That was a surprise for me when I saw the film."

Courtney explained how he imagined the scene while filming it.

"It's part of the roundup of the squad, so my interpretation was that he had been taken out by [Rick] Flag's crew," Courtney said. "But it's not specified [in the script]."

(Director Zack Snyder.Henry Romero/Reuters)

Warner Bros./DC heads could've had numerous options in mind.

There's Courtney's theory of it being one of Flag's (Joel Kinnaman) men. It could have possibly been Batman (Ben Affleck) capturing Boomerang, as he's seen in the movie nabbing Deadshot (Will Smith) and Harley Quinn (Margot Robbie). But it turns out the plan was always to have The Flash in the movie, according to "Squad" director David Ayer.

“Flash was always in the movie," Ayer told Collider. "We just got lucky because 'Justice League' was happening and they had the uniform, they had the assets, so we were able to get that photography.”

So instead of having Miller show up for literally one shot during production of "Suicide Squad," Ayer confirmed to Collider that "Justice League" director Zack Snyder directed The Flash portion of the Boomerang capture scene while shooting "League" in London and sent the footage to Ayer, who was in postproduction on "Squad."

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