During the end credits, an animated version of a character resembling Nikola Tesla appears looking down on Thomas Edison. Tesla was a genius whose credit was overshadowed by Edison, Tesla's employer, who took patent and financial credit for a number of Tesla's inventions. In recent years, Tesla has finally been getting the credit he deserves, which is arguably why he has a look of disdain towards Edison.
Edison did not in fact invent the light bulb, he only perfected the filament inside the bulb that produces the light. Earlier filaments did not last long before burning up. He also employed a team of almost one hundred scientists working for him so many of his credited inventions actually being invented by him personally is speculative.
Edison actually had nothing to do with Topsy's electrocution. This misconception most likely arose because the power was supplied by the Edison Electric Illuminating Company of Brooklyn and the surviving film of the electrocution was filmed by Edison's company thus the film has Edison's name on it. In fact there's no evidence that he was even at Luna Park that day.
The trivia item below may give away important plot points.
Idea: near the middle of the episode Bob reveals to Linda his "Spice-ceps." Later, Linda takes Bob's idea and perfects it by creating the "Spice Rack." Much like Edison did to Tesla (stealing and perfecting ideas) Linda does to Bob.