Chrissy Teigen, Patricia Arquette and more react to United Airlines leggings incident

— -- After United Airlines barred two girls from boarding a flight this weekend because they were wearing leggings, which the company said is part of their policy for relatives and friends of employees who travel for free on standby, actors and activists have taken to social media to criticize the airline's choices in the incident.

Activist Shannon Watts first tweeted the incident early Sunday, writing, "A @united gate agent isn’t letting girls in leggings get on flight from Denver to Minneapolis because spandex is not allowed?"

Watts is a mother of five and the founder of Moms Demand Action for Gun Sense in America.

After major news outlets picked up reports of the incident in Denver, a spokesman for the airline confirmed the report to ABC News, adding that two teens weren't allowed on the flight because leggings are "not in compliance with dress code policy for company benefit travel," a program that lets the airline's workers and their families travel for free, but within certain guidelines. "There are different rules for these privileges because people are flying for free," the spokesperson added.

Celebrities like actress Patricia Arquette and model Chrissy Teigen took to Twitter to share their concerns over the airline's rules for the program.

"This disproportionately affects women," Arquette wrote on Sunday. She also responded to another person's tweet, adding "Times change and discriminatory practices should be examined."

Teigen commented on past outfits she's worn for airplane travel and how she thinks those are far worse than leggings.

Even the "Star Trek" icon William Shatner got in the mix, posting a picture of him wearing leggings in the past.

Comedian Sarah Silverman commented on United's tweet that leggings are welcome, just not for this special free travel program. She added that she won't be flying United anymore for her upcoming tour.

Here's what others like Seth Rogen and George Wallace had to say: