The comedian - who sang The Beatles' 'I Am the Walrus' while dressed as Willy Wonka on the roof of a psychedelic bus - ripped his trousers and nearly got trapped on top of the van.
"I felt all right until I ripped my trousers just before I went on, and then my foot got caught in the trap door on top of the van, so it could have gone downhill from there," Brand told The Mirror.
Brand had predicted that Britain would "balls up" London 2012 but now believes the Games were a success.
"It was brilliant, I really loved it and I was so happy to be a part of it. There's just so much positivity has come from that Olympic Games, and I hope it continues to go in the right direction," he said.
"I've got Spice Girls mania all over again now, it's like going back to 1996 - and Stuart Pearce was even nearby too. I've got a massive crush on Geri Halliwell too, so everything in the world was as it should be.
"I met all the rest of the performers, everyone was lovely - it was a great atmosphere. I know the Spice Girls anyway but I met Tinie Tempah, I love that kid, and George Michael was really, really cool."
The star's new documentary Russell Brand: From Addiction to Recovery airs on Thursday night (August 16) at 9pm on BBC Three.
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