Per Bryan Alvarez, Darby Allin was legitimately hospitalised and AEW will now determine whether he can wrestle the rest of Continental Classic:
“What happened was he got hurt in the Kevin Knight match last week. The spot that looked the scariest was the Coast-to-Coast Dropkick. He got smashed with that move. I don't know if that's the move where he got hurt, but he got hurt.
He was in the hospital for a while, but they did clear him because he ended up going home. So he can travel. The impression I was given was they're going to find out more on Collision. He might stay in the tournament, and he might not. They have to figure it out in the next few days depending on how he's doing.”
(via Wrestling Observer Radio)