It turns out the Chinese fantasy epic “The Great Wall” actually dodged many of the criticisms of the trailer (Matt Damon does not singlehandedly save China), but there were apparently legitimate concerns brewing behind the scenes, according to The Wall Street Journal.

As one of the most expensive collaborations between Chinese and American film industries to date, “The Great Wall” stands as an experiment in cooperation between two markets that’ve become increasingly reliant on one another to make a successful movie.

But the approach to making a film differs in many respects in China, as filmmakers must navigate state-sanctioned censors, for example, and operate under relatively lax on-set safety requirements.

According to the WSJ, Damon’s physical health was a concern for the studio given the extreme levels of pollution in the capital city of Beijing, where the air quality from day to day can be considered hazardous. The coastal city of Qingdao was later selected as the location for filming because of its cleaner air.

“How do I look Matt Damon in the face when he’s the only one not wearing a mask?” a producer reportedly questioned in a meeting.

The conditions for crew members were apparently also questionable as workers were reportedly using a type of sealant that’s banned on other sets.

“I nearly passed out from the fumes that came out of a spray can,” one crew worker reportedly said.

Monitoring harnesses and safety devices proved to be another issue while filming the action-heavy film, according to key grip Guy Micheletti, who told the WSJ that harnesses were “routinely ignored” when the scenes called for climbing scaffolding. He likened his job on set to being a “policeman.”

“The Great Wall” has already proven to be a box-office hit in China, but the jury is still out on its marketability in the U.S. ― the film has yet to be released domestically ― considering some critics railed against the film’s trailer for upholding a white savior complex and whitewashing Chinese history.

“The Great Wall” hits theaters Feb. 17.