Fire trucks and ambulances soon arrive and outside Bryan insists: "This is not a joke, there really is a gas leak."
Perry then falls to the floor and says: "I'm not feeling good."
Meanwhile, the pop star has been joking with Richie about her claim that he won't be invited to her wedding because he's too expensive.
The Roar singer, previously married to comedian and actor Russell Brand, teased Richie earlier this month when she said he and Bryan wouldn't be getting invites to her upcoming wedding to Orlando Bloom because she "couldn't afford" their appearance fee.
Now, Richie has joked that he and Bryan are outraged, as they keep asking Perry details about the wedding but get no response.
He quipped: "It's time that we just put it out there. Luke and I are just offended. We keep waiting for Katy like, 'okay, when is the date and where are we supposed to be and how many songs do you want us to sing?' Crickets. Crickets.
"So we've kind of taken it to a point now where no, we're not invited. No, they don't want to see us."