Revealing mistake: When Luke jumps from Jabba's prisoner's skiff over to another skiff, if you watch Lando hanging underneath the prisoner's skiff, you can easily see that he is a matte painting in this shot, because he doesn't move at all.
Revealing mistake: When Jabba's sail barge begins to explode, you can see that one of the floating skiffs is standing on stilts. (00:36:30)
Revealing mistake: The interior matte painting of the hangar on the Rebel ship holding the stolen Imperial shuttle doesn't match the appearance of the hangar from the exterior shot of the Rebel ship. The interior hangar shows an extended platform and four banks of vertical lights bordering the opening and then walls. From the exterior, the hangar appears to have a big light bank near the opening, and then thinner light banks behind it spaced further apart than the interior shot. The exterior shot also doesn't have a platform. (00:50:45 - 00:53:20)
Revealing mistake: When Luke and Leia swing from the deck on to the skiff, you can see that the man playing Lando Calrissian is not Billy Dee Williams but his stunt double.
Revealing mistake: In many of the scenes taking place in outer space, if you look closely you can see polygon borders surrounding space vehicles (X-Wings, Star Destroyers, and even the Death Star) indicating the objects being superimposed into the outer space background. [This mistake may only apply to the Blu Ray version.]
Revealing mistake: In an overhead shot of Darth Vader throwing the Emperor to his death down the Death Star reactor, you can see that it is a dummy in the Emperor's costume and not Ian McDiarmid.
Revealing mistake: The close-up of R2-D2 waiting for Leia to return has a clear shot of the middle wire section of C-3PO in which you can see Anthony Daniels breathing as the spandex underneath the wires expands. This is especially clear on the Blu-ray. (01:02:00)
Answer: The Jedi are shown to have something of a blind spot in regards to matters of the heart. Note that when Luke confronts Obi-Wan over lying to him about his father's fate, Obi-Wan's response is haughty and defensive, and gives Luke nothing in terms of regret or apology. They're focused on their mission, not on how Luke feels. Why waste time, in their eyes, telling Luke about his mother? If they had their way, he wouldn't even know about his father. The prequels would make this more explicit, showing that the Jedi are conditioned from the beginning to let go of all "passions" because they could so easily be corrupted, and their inability to understand Anakin's emotions just contributes to his downfall.
TonyPH