David Corenswet may show off his superhuman strength as he battles villains in the upcoming Superman film, but while filming another project, the actor was literally knocked down by an inanimate object.

While working on a major dance sequence for the new Apple TV+ series “Lady in the Lake,” the Philadelphia native slipped down the stairs and injured his shoulder, co-creator and director Alma Har’el told TVLine. Corenswet required medical attention and a choreographer had to step in for parts of the scene.

MORE: “Superman” actor David Corenswet congratulates the US Olympic hero on the pommel horse, who looks like Clark Kent

There are some spoilers for episode 6 of “Lady in the Lake” below.

“Lady in the Lake,” which premiered last month, is about the disappearance of a young girl in Baltimore in 1966 – and interweaves the lives of two women, Maddie Schwartz (Natalie Portman) and Cleo Sherwood (Moses Ingram). The latest episode, which premiered Friday, includes a dream sequence featuring an elaborate dance number that Maddie imagines while lying unconscious in the hospital.

Corenswet, who plays Maddie’s ex-boyfriend Allan Durst, is one of the dancers in the dream ballet. Disguised as a sailor, Corenswet was asked to perform a difficult tap-dancing sequence down the stairs, which made the crew uncomfortable.

“We rehearsed so much and were incredibly worried that he would fall down the stairs and hurt himself,” Har’el told TVLine.

To reduce the risk, the production team constantly cleaned the stairs to prevent Corenswet from slipping. But during a break, when Corenswet went to get coffee, “he fell down the other stairs,” Har’el said. He injured his shoulder, required medical attention, and had to stop filming for the day.

The production team decided that a choreographer of similar stature to Corenswet could step in for the remainder of the shoot that day.

“They look kind of alike, and we’re going to use him,” Har’el said of the choreographer. “We take the costume off David and put it on him. And as we say that, we see the paramedics cutting the shirt off David’s body. … It was an unforgettable day.”

Har’el said that everything worked out for the dance scene – they used half of the previous footage of Corenswet and half of the choreographer who looked like him – and that Corenswet is perfectly fine after his slip-up.

“He was a hero,” she said of Corenswet.

This year has been a busy one for the rising star. Last month, Corenswet packed Production of “Superman”, the first film in the new DC Universe film series, the is due to be released next July. He also appeared in the romantic musical “The Greatest Hits” in April and played a villain in the summer blockbuster “Twisters.” The finale of “Lady in the Lake” will air on Friday.