Star Wars: The Force Awakens Trailer

[Fragenstein]

I'm fairly sure Luke's lightsaber is actually green and not blue as from end of ROTJ.

Sure that saber could be his original one that Anakin his father had before him but I think if necessary Luke knows enough to build himself a new lightsaber if his old one broke...

I'm a little confused on this one. The blue saber, which Anakin lost along the way before constructing his Sith-red version, and which was passed to Luke by old Ben, was dropped down that massive air shaft on Bespin along with Luke's severed hand. Possibly even all the way out of the mining colony and into the gas giant.

I'd have to watch the scene again to see if it ended up over the same trap-door that plopped Luke onto a handy weather-vane. I seem to remember some random piece of hardware clattering along the slide with him, but it's been a LONG time. Obviously Luke stopped using it immediately after for whatever reason.

Vader even commented on the green saber:

[igniting Luke's saber]
Darth Vader: I see you have constructed a new light saber. Your skills are complete. Indeed you are powerful as the Emperor has foreseen.

Now, it may be that it ended up in some cranny of mining colony and was rescued. Which, to be honest, is something I've been wondering since 1983. So it would be nifty if it actually appears again.