When Peter as Han Solo is revealed in carbonite as Jabba's "favourite decoration", he's looking over his left shoulder while mooning. But when he was encased in carbonite during Something, Something, Something, Dark Side (2009) he was looking back over his right shoulder.
When Peter/Han was tied up to be roasted by the Ewoks, they were starting the fire under him, and in the next shot of him the fire is not there at all.
When the Rebels are fighting around the Death Star, one view shows the unfinished part of the Death Star to the right of the Starkiller, yet another shot shows the unfinished part to the left.
Before Chris dressed as a Jedi breaks Stewies neck while dressed as Darth Vader, the spaceship ramp behind him is at a very steep angle. The next scene when Chris walks up the ramp with Stewie the angle is now less steep than before.
When Peter is defrosting from being in Carbonite, he is flashing his rear whilst emitting wind. When he hits the floor though, his pants are now pulled up when Lois is about to pick him up.
The giant Rush Limbaugh monster says, "No tax-dodging Jedis in my pit!"; the word "Jedi" is both a singular and plural noun, so no "s" is added to the word to pluralize it.