Pigs and other mammals have dichromatic vision, or only two pigment cones that create colors. This means a pig's view of the world is less rich than a person's, but that a pig can still differentiate colors. Animals with monochromatic vision have only one pigment cone and see in black and white. Therefore Arnold wanting a color TV is appropriate.
When the two bank robbers note that the Douglas farmhouse calls to mind "Tobacco Road," they are alluding to the title of Erskine Caldwell's 1932 novel that was subsequently made into a movie, i.e. Tobacco Road (1941), the plot of which revolved around the hardscrabble life of a family of tenant farmers.
Adjusted for inflation, the $67 stolen from the bank, plus Arnold's $5, would equal approximately $660 in the year 2023. The insured value of $42,000 for Lisa's ring would be about $385,000.
The names of the two bank robbers, i.e. Barney and Clyde, spoof the portrayal of real-life bank robbers Bonnie Parker and Clyde Barrow in the movie Bonnie and Clyde (1967), which was released to theaters in August 1967 and still playing in some theaters when this episode originally aired.
Lisa's ring, taken by the robbers, is insured for $42,000.