The actor apparently fell asleep while driving the 45-minute home trip after midnight. He was reportedly unharmed and was taken to a local hospital for observation and later on discharged.
However, his car was wrecked in the incident.
Those who work in the film industry have long complained about the unsafe working conditions that demanding hours can cause.
"This is an extremely troubling situation and we are deeply concerned about the safety of performers on the 'Riverdale' set," the union said. "We are sending a team to Vancouver to review the circumstances surrounding safety issues affecting performers on this production. We have no further comment at this time"
Warner Bros. Television released a statement refuting some of those claims.
"First and foremost, we are extremely grateful that KJ Apa was uninjured during his recent accident. Secondarily, we want to specifically address the characterization that conditions on the set of Riverdale are of concern," reads the statement.
"We have a large cast of series regulars, and our actors do not work every day. On the day of the accident, KJ worked 14.2 hours. The previous day he worked 2.5 hours, and the day before that he worked 7.7 hours. KJ has repeatedly been informed about making production aware if he is tired or feels unsafe, and if so, either a ride or hotel room will be provided for him. The accident occurred last Thursday. Additionally, it is untrue that KJ was taken to the hospital. He was treated by first responders on the scene and released by them. We also sent a doctor to his home later that same day for a follow-up to confirm his well-being," the statement concluded.