When Dilbert, Ratbert, and Dogbert are escaping the authorities there is a sign that says 'Townbert'.
In Episode 12, (Holiday), Dilbert is trying to watch the "Pine Cone Celebration Parade", Dogbert suggests he watch it in person, and Dilbert responds that he wouldn't get to hear the commentary. As they cut to the commentary, they mention that the parade is in Seattle.
Female Commentator: "Look Phil, It's another one of those big things... What are they called?"
Phil: "I think that is called a float, the name originated right here in Seattle, yup"