See video and pics of Jim Carrey, Zooey Deschanel and Danny Wallace at the Yes Man premiere
He explained: "I was doing a pratfall. I've done pratfalls my whole life but half way through the pratfall, I decided, 'I'm going to change things up here - I want to get all my limbs up into the frame and I hit so hard'.
"But the first thing I thought of was 'must look cool, man'. I got up and I was in agony. I went up to the video monitors and I said 'Can I see that back?'"
She said: "I came in the next day and he was just sitting there like normal and everyone was like, 'Jim cracked a rib yesterday, so just so you know he might not feel well'. But he was such a good sport about it."
He told BANG Showbiz: "I got here on a double-decker tank bus - with canons!"
The American actor admitted he was feeling the December chill, but insisted he could handle it for one night.
He said: "The cold is nice - because I'm just visiting."
The star - who claims he has to say 'yes' to "most things" girlfriend Jenny McCarthy asks him to do.
Carrey held a loud hailer and told the waiting crowd: "There is nothing to see here".
Speaking on the red carpet he said: "It was a little strange up there. I couldn't tell if they could here me or not. I couldn't hear myself, I had no idea what I said."
Zooey looked absolutely stunning.........like a porcelein doll.......and i loved Jims scarf, a nod to Anglo American relations, too many Brits want this to bomb.