The scene title card "The Hole in the Head Gang" is a takeoff on "The Hole in the Wall Gang," a gang in the American Wild West. It took its name from the Hole-in-the-Wall Pass in Johnson County, Wyoming, where several outlaw gangs had their hideouts.
Frasier mentions the family traveling at 70 miles an hour when they were kids. This would sound like speeding back in the 60s, but in fact the speed limit in most states was 75mph, and in the northwest, some states had no speed limits at all.
The episode's title is probably a reference to the John Steinbeck travelogue, "Travels with Charley: In Search of America."
The scene title card "Checkpoint Charlie" refers to a famous Berlin Wall crossing point during the Cold War.