The Flash 's Back to the Future gag has a basis in reality

Warning: This article contains mild spoilers for The Flash.

Of all the timeline disruptions that occur in The Flash due to Barry Allen's time tampering, one of the more amusing changes concerns the state of Back to the Future.

Barry (Ezra Miller), a.k.a. the Flash of The Flash, uses his speedster powers to travel back in time and stop his mother's murder, but he ends up drastically changing the course of history — including Hollywood history. Conversing with his past self (and his past self's roommates), he realizes, to his horror, that actor Eric Stoltz now plays Marty McFly in the 1985 classic Back to the Future instead of Michael J. Fox.

For those unaware, a Fox-less, Stoltz-starring Back to the Future was very nearly a reality.

Everett Collection; Warner Bros.; Jamie McCarthy/Getty Images Michael J. Fox in 'Back to the Future'; Ezra Miller in 'The Flash'; Eric Stoltz

It's one of those classic Hollywood stories. Fox was the first choice of director Robert Zemeckis and screenwriter Bob Gale to play Marty, the puffer vest-wearing teen who travels 30 years back in time in a DeLorean with Christopher Lloyd's Dr. Emmett Brown. Unfortunately, the actor's schedule didn't align with the production's so they cast Stoltz, who had previously starred in Fast Times at Ridgemont High and Running Hot. Stoltz, however, was eventually let go a few weeks into production because Zemeckis and Gale felt his reading was too intense.

"You know what I didn't know about the whole Eric Stoltz thing?" The Flash director Andy Muschietti remarked during an April press conference in Los Angeles timed to CinemaCon. "Of course I knew the Eric Stoltz story for a long time, but I didn't know that when Eric Stoltz is fired, the one that is also fired is the actress that plays Marty McFly's girlfriend."

Melora Hardin, the actress who would go on to play Jen in The Office, had been cast as Marty's girlfriend, Jennifer Parker, opposite Stoltz. When Fox, who was now available to play Marty, took on the role following Stoltz's departure, another change had to occur.

"They fire [Hardin] as a ripple effect because, when they bring Michael Fox, he's so tiny in comparison to Eric Stoltz," Muschietti explained. "Melora Hardin was like three feet higher than [Fox], so they had to hire a shorter actress." That actress was Claudia Wells, who, like Fox, hadn't originally been available to play Jennifer due to scheduling conflicts.

But, in another reality — The Flash's reality, specifically — Stoltz is still Marty McFly and Hardin is still Marty's best gal. The major downside in this alt-timeline is the unfortunate Stoltz/McFly tattoo on Barry's roommate.

The Flash is currently playing in theaters.

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