Not sure if these have been already mentioned, but visuals are always fun
Chewbacca crushing set step after 3PO gets shot
Luke's Lightsaber is not in same spot from where it fell, to when he uses the Force to pull it back into his hand. Also, the second shot is a flipped negative of the first (I flipped it back)
After R2 gets the door open, he exits, then comes back into the hall lets off his fire extinguisher, then exits a second time
After the Slave I leaves, this close up in R2's dome we see a reflection of what appears to be the rectangle of the camera lens next to the stage light.
