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. Another issue is the fact that Drew Carey no longer has a good relationship with ABC after the handling of the show's final season and the way the network unceremoniously pushed him out after he spent a decade doing everything they asked of him.
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 two season renewal after the seventh 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).