Other mistake: In the cut scene at the end of "Rescue the Princess" in A New Hope, Leia shoots the grate and gives the gun back to Luke before she jumps down it. However when they show the hole again,the gun Leia used can be seen sticking just out of the top of the hole.
At the end of episode five, Luke has had his hand cut off by Darth Vader. When he falls into the Millennium Falcon, if you look very closely, he still has both of his hands. In the next scene, his hand is gone again.