When you’re the leading man in a film that needs you to pull off some pretty impressive stunts, the last thing you want to do is break both of your arms on the second day of shooting. And yet, that’s exactly what happened to Jeremy Renner on the set of action comedy Tag, which follows five adult pals who have played the same game of tag for three decades, with Renner’s character avoiding getting tagged each year.

This is why in the final edit, both of his arms are CGI. Many people believed the actor had hurt himself while portraying the arrow-wielding Hawkeye in the action-packed Avengers: Infinity War when the ailment was originally announced. Audiences now know the truth about Renner’s injuries because his character did not appear in that film.

“The movie’s about a real group of guys that have played the game tag since they were 9 years old. They’re in their 50s now and they played it over these last 30 years and every year in the month of February it’s game on. They play,” explained Renner.

“There was this stunt on the second day of the movie where I was avoiding all of the guys,” began Renner. “So I do this stunt.”

“It’s a stack of chairs, like 20 feet high, and it’s supposed to fall over and I’m supposed to ride it down like a surfboard and then keep running,” he said. “So that happened a couple of times and it wasn’t quite good enough, so let’s do it again, but the hinge broke. Anyway, the stack of chairs was supposed to go and it didn’t go and I went.”

“It fell and I broke both, well I didn’t know I broke my arms. I just fell on the ground and I’m like, ‘That kind of hurt. Let’s do it again,’” he said. “I went up, did it again and it fell. I’m like, ‘Ah, OK. Whatever.’”

“I thought they kind of hurt. I figured I should go to the trailer, gotta rest for a minute,” he recalled after the injury. “I’m like, ‘Ah, I have to go to the hospital.’ They already swelled up.’” He was subsequently informed that he had shattered both his radial and wrist bones, giving him two broken arms.

Renner added that the first week of filming after the incident was difficult since his broken arms were bloated, but after the swelling subsided, things became a bit better. Throughout the rest of the shoot, the actor wore splints and worked with a physical therapist.

Following Renner’s costar Jon Hamm’s revelation on The Ellen DeGeneres Show last week that Renner’s damaged arms were CGI’d (although emphasizing that he had no role in the tragedy), some have speculated just how much of Renner’s Tag performance required visual effects.

Renner had to return to work on Anthony and Joe Russo’s Avengers 4 once Tag finished, and his arms were much needed. Renner claimed that while filming, he went to daily treatment and that it was a “battle of will to heal.” The actor worked really hard to ensure that his injuries did not cause any production delays. EW quoted Renner as saying:

“What else do you do, you just stop and cry and everyone go home? You know what I mean? I’d be like, ‘sorry guys, I’m not going to use a bow and arrow now in Avengers,’ it’s silly, so I have to kind of push through so that you can perform for everyone.”

After host Jimmy Fallon appeared shocked by Renner’s choice to keep filming, he said, “I had to keep going, man. Otherwise, I had Avengers to do after that. I had to heal fast.”

The actor emphasized that CGI was only utilized to conceal his arms in the moment where his character climbs the stack of chairs.

“I went back to shoot that day, I didn’t take anything out of the cast and they had to put like a clean sleeve over my arm, because I didn’t want to take it off right after I just broke it,” he said. “I needed it to set, I wanted the bone to set, so I think they had to CGI my arm or something in just that one scene, but the rest of it, you know, it all went on okay.”

Hamm joked that “mercury in retrograde” was caused by his absence from the set that day (he was in London for the premiere of Baby Driver).

“When I left, everyone was fine, and when I came back, the s— had hit the fan,” Hamm told EW.

“Jeremy is such a trooper that he then continued shooting, because between his Avengers schedule and everything else he does in his life, there was no option other than to keep going and he showed up the next day with these two casts on and we’re obviously all very careful and we had to tweak some of the moves and some of the stuff to make sure that he didn’t hurt himself further, and then you just clean up the casts in post,” he added.