Executive Meddling: The only reason why Steve (John Carroll Lynch) stopped dressing in drag halfway through the show's run. ABC executives told the producers to make Lynch dress masculine due to "negative audience feedback."
Keep Circulating the Tapes: Only the first season is available on DVD, and it's likely to stay that way for the forseeable future. Copyright issues over music have prevented further seasons from being released, as Drew Carey is insistent on the DVD release being identical to the broadcast.
Out of Order: ABC aired most of the episodes in the final season badly out of production order, causing confusion with the story lines, though TBS aired the episodes in the correct order.
Screwed by the Network: The show was a ratings hit so ABC gave it a three-season renewal after the sixth season. Then ratings started to fall during the eighth but ABC found themselves contractually obligated to produce and pay for two full seasons of a show they didn't want. The network, realizing that the contract didn't obligate them to broadcast the show at a decent time, got back at the show by putting it in strange time slots and burning off the final season during the summer of 2004.
Stephen Fry and Hugh Laurie were both offered the role of Mr. Wick initially.
Before the creation of Kellie in Season 8, Kate Walsh (Nikki) was offered to be a series regular, but she declined (instead she only appeared in the first 3 episodes of Season 8, before being written off).
ABC execs originally didn't want Ryan Stiles appearing on both Drew's show and Whose Line Is It Anyway? at the same time and originally told him to choose one or the other. It wasn't until Drew got the job to be the host of Whose Line...? that they backed off the issue.
They really wanted Christa Miller to come back for the series finale. The proposed idea was that Kate would appear in a dream sequence, and would speak to Drew convincing him that marrying Kellie is the right thing to do and that they really are meant for each other. ABC execs refused to allow a guest appearance because they felt it would be like free advertising for Scrubs, which was airing on NBC, a rival network (which is ironic given that ABC would air Scrubs years later anyway).
You Look Familiar: Robert Torti had a recurring role in season 1 as Kate's boyfriend Jay, who broke up with her and left the show early in season 2. Torti returned a few seasons later in "What's Wrong With This Episode? IV" as Nick, who also is dating Kate.
Greg Proops appeared as himself in all the "Drew Live" episodes (along with several other Whose Line? cast members). But, then he bizarrely turns up in an episode a few seasons later playing a Winfred-Louder employee.
Joe Walsh appeared as himself in one early episode, then appeared several episodes later as a friend of Drew's who appeared in his Ramada Inn band.