Hippie drug guru Timothy Leary's expertise in botany and pharmacology as Dr. Milo in "Stagecoach"...not to mention his Fauxlosophical Hand Contemplation scene.
John "Gomez Addams" Astin mentioning how the [John & John Q.] Adams family was "weird".
The series finale features a group of villains who are all played by football players, and discuss their plan to capture Brisco in the same style as a football play, including shouting "Break!" at the end. While running down a street, they encounter props which conveniently resemble a football training camp obstacle course, including tires.
The traveling scenes are denoted by a very Indiana Jones -style red line on a map overlaid with video footage, which falls more within Author Allusion.
Reality Subtext: Originally, the writers envisioned the rivalry between Brisco and Bowler lasting longer. However, as Campbell and Carry had such strong chemistry, the writers were compelled to have them interact more often - leading to Brisco and Bowler becoming close friends sooner than expected.