Amber Heard, 31, was just cast to play the mom of an 18-year-old in indie flick 'Gully'

For all the progress Hollywood's supposedly trying to make, some casting decisions sometimes appear a bit... outdated.

Amber Heard, who is 31 years old, has officially been cast to play the mother of 18-year-old actor Charlie Plummer in upcoming indie drama "Gully."

It's unclear what age Heard's character is supposed to be in the film, but if the movie depicted their true ages, Heard would have given birth to Plummer at 12 years old.

"Amber Heard is 31 and she is already getting roles playing the mother in movies," one Twitter user mused.

"Gully" is directed by Nabil Elderkin. The film follows "three disaffected teenagers, all victims of childhood trauma, who are running a hedonistic riot," Variety reports.

For some, the casting news may reinforce the notion that female actresses are "aged out" of Hollywood -- as male actors get older, their love interests get younger.

“Honestly, it’s so annoying," Helen Mirren said in 2015. "We all watched James Bond as he got more and more geriatric, and his girlfriends got younger and younger. It’s so annoying."