This show features the debut of the second Coyote, the one built around a DeLorean, which replaced the original Season One version because it was too small for Brian Keith to get out of effectively.
Hardcastle references Halley's Comet. This comet is visible with naked eye and at time this was broadcast it was less than 2 years before the comet was due to make it's every 76 year pass. It was already a very popular subject.