Of course the entire sky-car sequence in AOTC seems to be a rip-off of the sequence in The Fifth Element. I could forgive that, but George took it a little too far over the top for my tastes.
The part of Anakin jumping from ship to ship was ripped off.., I mean an homage to an episode of Flash Gordon.
I'm always taken out of the moment when:
In Jedi, Greedo's dialogue to Han Solo is heard in Jabba's palace
The Rebels are actually captured by Ewoks. It is one thing to put up with those stupid little fur-balls, but to actually let them tie you up and almost barbeque your friends? Not gonna happen.
I always get bugged when there is a situation where the Jedi ought to be using the force to escape (like the restraints on Geonosis), but they end up doing everything the hard way.