- Mark Slackmeyer's public-radio show is called An Urban Home Companion. Just like several real NPR shows whose titles are take-offs of other NPR shows.
- Duke's perpetual 40somethingness may be a case of Fridge Brilliance. All the drugs he's been subjected to over the years - including temporarily being made a zombie in Haiti - may have embalmed him alive.
- Word of God is that Duke and Hedley aren't aging at the same rate as the rest of the cast because they're more concepts than characters at this point.
Fridge / Doonesbury