When Luke is looking for R2 with the macrobinoculars you can clearly see a rope pulling a droid across the screen.
In the shot where Luke and Ben first see the Millennium Falcon the Falcon has no radar dish. This is because only half of the Falcon was constructed for this scene. But I think a dish could have been matted in fairly easily.
After the Falcon takes off from Mos Eisley, Ben can still be seen walking out of the cockpit - after he had already strapped himself in at the chess table.
Right after Gold Leader says "Red Leader this is Gold Leader" the two Y-Wings outside his cockpit window disappear for a frame.
Right after Vader says "I have you now" the TIE fighter on the left disappears for a couple of frames.