In STAR WARS ep VI, Jabba the Hutt appears to mirror himself during a scene where he drinks wine. Hutt monsters are not known to have mirroring ability.
In STAR WARS ep IV, you can clearly see a camera set reflected in C-3PO's armor in multiple scenes, notably in Federation spaceships. If STAR WARS really happened there probably would NOT be cameramen filming the droids in such stressful scenarios.
In STAR WARS ep IV, when R2-D2 is aboard Jawa transport, you can clearly see a man inside of the machine. Nowhere in STAR WARS culture is it ever mentioned that the R2 series are powered by tiny men or perhaps children.
During the final battle in ep VI, you can see that the lightsabers cast shadows. This should not be possible as sources of light do not cast shadows.
In Star Wars ep V, after Luke's hand is cut off by Darth Vader, you can clearly see that he is just hiding his hand inside of his shirt. This contradicts the later story developments.