Some of the photo-shopped images of Krusty feature him as: Neil Armstrong, the soldiers at Iwo Jima, the Tank Man, and Jim Leavelle, the Dallas police detective escorting Lee Harvey Oswald through the basement of the Dallas police department when Oswald was shot and killed.
The bit with Krusty complaining about the FCC not allowing him to say certain words on the air is a reference to George Carlin's 7 words you can't say on TV
Mayor Quimby's quip about his regretting building his lover an opera house after hearing her voice for the first time was a reference to Citizen Kane in Rosebud, specifically his making a similar mistake.
In Krusty's campaign commercial, the voiceover saying "The man from funny" is a parody of an ad for Bill Clinton in 1992, where Clinton was a the man "From a town called Hope."
When the plane hits the living room of the Simpsons' house, it reversed by itself. Planes cannot reverse by themselves. They will need a pushback car or must turn around.
When Krusty says he's on Pepto and Xanex, Marge's pearls and Lisa's dress turn to a light orange.
Planes can't fly so low. (unless on approach and at takeoff which is likely the situation plus with the perspective the planes are likely higher than they seem)
Marge says the family hasn't had a decent night's sleep in weeks, however flights aren't allowed to operate between certain times (night).
Krusty's navel can be seen when wearing the tank-top in his offensive sketch.
Krusty tells the Gun Nuts to relax he can't touch them but Republicans love the Gun Nuts
Krusty is not evil enough to be a Republican though he is close enough!
Krusty is shown to be with the Simpson family in a hotel room on the night of the election. Most political candidates, especially those running for a seat in the United States Congress, typically hold rallies on election night, where the candidate gives a victory or concession speech (depending on the outcome) to a room full of supporters