Homer unknowingly setting the seat of his pants on fire when he uses the teleporter to bypass the stairs in the house is an even funnier gag for those who have seen The Fly (1986) and know why this was never an issue for Jeff Goldblum's character...
France bombing Springfield in The Homega Man will almost certainly be seen as an act of war by the American government. The American military will be deployed to invade France, if the United States doesn't respond by sending a neutron bomb of their own in retaliation.
In "Fly vs. Fly", Flyhead-Bart shows a disturbing degree of intelligence, eavesdropping on Bart and Lisa's conversation and attempting to kill her and Fly-Bart to prevent her from using the teleporter. With that in mind, it's possible the switch might have affected it in more ways than one...
The Reveal during "Easy Bake Coven" makes apparent no one in Springfield really expected to have a real witch on their hands. And the start of the episode makes clear they've went through a lot of residents. Given their insistance on accusing someone that day, they go from suspicious paranoiacs to restless murderers.
