This episode was postponed and not shown for a while due to the two lines: "The Sniper attack at the all star game was a blessing in disguise" and "Any child caught outside after the curfew would be shot". This is because in the real world around this time there was some pretty bad sniper attacks in Washington D.C so these lines were seen in a whole new light so they postponed this episode till enough time passed.
The movie "The Bloodening" is a parody of Village of the Damned (1960), which itself was based on a 1957 novel entitled The Midwich Cuckoos, in which women in a small village mysteriously fall pregnant and give birth to blonde haired children who may not actually be human
Dan Castellaneta ad libbed Homer singing "Hitler is a jerk, Mussolini...." It was added in to the episode only for the purpose of filling time.
Bart's chalkboard gag: Sherri does not "got back".
A deleted scene reveals that Superintendent Chalmers is an illegal immigrant from a Spanish-speaking country, with the kids addressing him as "Señor Chalmers", and Chalmers sheepishly muttering "Ay carumba" after being slapped by Agnes Skinner when hearing this.