Death of the Author: While Chuck Jones "Rules" of how the series was written is somewhat well known, his contemporary Friz Freleng considered his account of the series rules apocryphal, saying he made up the rules long after the original shorts were finished. Considering how often some of the "rules" were broken in the original shorts, there may be some grain of truth in that. Writer Mike Maltese also confirmed that there were no "rules" when they made the original shorts either.
Fanon Discontinuity: Rudy Larriva's eleven Road Runner shorts (and, arguably, Robert McKimson's two efforts along with the Sylvester/Speedy crossover directed by Friz Freleng) tend to be considered part of WB's Dork Age.
I Love Nuclear Power: A common Fanon for why Road Runner has superior running abilities to the Coyote despite the opposite being true in Real Life, given the cartoons' U.S. Southwest setting and Real Life events at the time of their creation.