Did WABAC machine alter history?
Think about it. Peabody & Sherman use the WABAC to visit a moment in history(invention/discovery/ect) that's pressumed to be a historical done deal. No sooner do they get there/then, circumstances are such that said history can only come to pass via intervention from Peabody & Sherman. This side of the "4th Wall", it's easy to see why-there would be no show. But every time travel story has it's anomalies, & it's always fun to ponder back stories to 2 dimentional shows. In Emmetbrowneze, does the arrival from the WABAC cause a rift in the Space/Time continuum that must be rectified? Would the egotistical Peabody "own up", or would he spin to save face?
A possible time-travel parallel could be some of the Star Treck movies, In the latest, an old Spock from the future told a young Scotty from the past that he invented trans-warp beaming. Of coarse, this was an already altered history after/before the supernova. The other possible analogy could be STIV The Voyage Home, when Bones & Scotty gave the polymer company CEO the formula for transparent aluminum. He was the one who invented the thing to begin with. Could be something like an ontological paradox.
At any rate, PIH seems to have its own unique "rules" as a time travel show
Kyle: It's bigger than Cartman's @$$!
Eric: No it isn't you guys