(2001, dir Jerry Zucker)

“Cuba Gooding Junior steals an MCI MC-9 coach (with fleet name Grande Charter]) filled with Lucille Ball impersonators.”

“The bus eventually has a flat tyre and overturns.” (thanks Bruce Korusek). \ Whoopi Goldberg and Lanei Chapman are bundled on board a school bus-type International:

At the end of the movie all the stars find themselves aboard a British open topper, also driven by Cuba Gooding Junior:

James Prince confirms my suspicion that this is ex-Bournemouth Daimler Fleetline CRU186C, owned from 1997 by Coach Engineering of Burbank, California. This bus also saw service in London on sightseeing tours.