I had suggested before that Luke was stood by the window of the council chamber (taken from the Bonfire scene from Ewok celebrations) the flames reflecting off his face could be explained as fireworks over the city. when he turns around we see ben sitting into his old chair (Bens hut scene from ANH) as he puts his hand to his chin who looks over at Yoda in his old chair..
there is more to it than that but it is doable IF you have the skills & the software to do it all in.