This may or may not be common knowledge. I did a quick search but came up with nothing.
Most of us have alwyas accepted the fact that the ESB scope is backwards while the RotJ scope is attached correctly. We believe this because we have clear publicity stills showing the ESB scope on backwards while the RotJ rifles on tour have the scopes attached the right way.
However, when Boba drops down to the skiff and raises his blaster to fire on Luke, the scope is CLEARLY on backwars, a la the ESB blaster. In all of the publicity photos I can find from that time period, the scope is on correctly, even from the famous skiff publicity photo. However, most recent publicity photos for the SE, in which Fett is holding the RotJ blaster which only has half of the cutoff scope, shows the scope on bacwards.
The point? From what I know, we have always assumed the RotJ scope went on correctly, but screen proof shows, like the ESB, you would be screen accurate to put the scope on backwards.
PS. I went back and looked at the Jabba's palace pics and while it is not entirely clear, it appears that the scope is on correctly, so maybe only the one blow apart gun had the scope on backwards.
If this has already been pointed out by someone else... well, what can ya do? Just trying to share something that is new to me.