Just in case this is still a thread about childhood misconceptions....

When I first saw the promotional photos that came out prior to the release of ROTJ, I thought that the new death star was just what was left of the SW ds after being blown up.......yup.

And when Luke cut off Vader's hand and I saw the wires I (briefly) thought "oh my God darth vader's a ROBOT!" I also, briefly, thought that it was Ben underneath Vader's mask when Luke took it off (now THAT would have been a twist!). ;-P