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Brad Sherwood and Colin Mochrie revealed in an interview at the New-York film academy that Drew Carey was a big fan of improv and wanted to give it a proper stage which is why he got involved with the show. However, Carey had no previous experience with improv as a performer and just wanted to host the show. It was the ABC's executives decision to have Carey improvise with the other performers. As soon as they found out, all cast members took Carey to different theaters and comedy clubs to teach him the art of improv.
Drew Carey often jokingly introduced the Hoedown as "Our favorite game in the whole wide world." The cast members hated it with a passion. Ryan Stiles hated it so much that many of his songs insulted Carey, the Hoedown itself, or both.
The Whose Line crew was such a well-oiled machine that they could shoot 9 to 12 episodes on a single weekend. Shooting a whole season took only three or four weekends every year. The cast revealed it was one of the reasons they were so great together and had great relationships with each other, because they didn't have to spend that much time together.
When Robin Williams was a guest performer, his hair was blond. He was working on One Hour Photo (2002), and had dyed his hair for the role.