Fridge Horror: The Battle of Endor from It's A Trap! is a lot more disturbing than what's shown in the actual film, but all they did was avert the Bloodless Carnage trope from the original film. The Ewoks still behave the same as they did in the original film.
Harsher in Hindsight: You know the scene where Peter/Han has various Stormtroopers dig their own graves using their own helmets as shovels and then line them up to be killed, that he did in order to "make the film darker?" Well, the 2012 Essential Guide to Warfare kind of shows that the Ewoks during the battle essentially did something similar.
Quagmire's German voice actor (Hans-Georg Panczak) was the dub voice for Mark Hamill's Luke Skywalker in the German translation of the original Star Wars movies (Episodes Four, Five, and Six from the late 1970s into the 1980s).
Also, Osama Bin Laden saying "Still Alive" after popping out of the Tatooine desert? Yeah, that wouldn't be true three weeks after the episode premiered.
In "Blue Harvest," a shot of TIE Fighters flying outside of the Death Star is capped off by a single, repainted TIE blasting some dope beats from its subwoofers. Star Wars Rebels sees Sabine, the Ghost's resident explosives expert and art aficionado, spruce up a TIE Fighter her buddies hijacked several episodes earlier with a similar paint scheme. No subwoofers, but it does come with an electromagnetic pulse.
In "Blue Harvest," the Death Star's infamous Achilles' Heel was "kind of an aesthetic choice by the architect". Come Rogue One, and that turns out to be true: Galen Erso, the chief designer of the Death Star, built it on purpose as a discreet form of sabotage.
Sequelitis: It's generally agreed that "Blue Harvest" is an amusing one-shot episode that's simply the end result of the show already doing so many Star Wars gags. Doing the other two films from the trilogy ruins this joke and, as the show is often want to do, takes an Overly Long Gag that works once and continues to do it until you forget why it was ever funny in the first place. Even the creators hated them.