Quoted from Riffbear:
Why is that sometimes the targets are lit in a light blue color?
By shooting those - what do you achieve?
Also how do you light Extra ball?
The 5 stand up targets? Those are the Jedi Training targets. Shoot all 5 within about 30 seconds to advance your Jedi level (Youngling, Padawan, Jedi and Master). They also advance your FORCE targets by one for each completion. If the target is already lit up it's because it's already been hit. If it's flashing it's because it's about to time out and if timed out they will all reset. The higher your Jedi level the more points each target gives you.
Sometimes just for fun I use Luke and select his Jedi Training path on the first ball (and any other balls) and try to advance his Jedi Training to a point where after completing Hoth 2 and then Escape from Hoth mini wizard mode I enter Lightsaber Dual ASAP with a x40 multiplier. Not a bad way to practice both Escape from Hoth and Lightsaber Dual and not to mention it's not bad at improving your average score.
Lighting Extra balls can be randomly obtained at the end of each mini wizard mode, Escape from Tatooine, Escape from Hoth, Battle above Endor and Destroy the Death Star. Also from random pop bumpers and Mystery rewards. I also have a gut feeling that moving the multiplier when it's down to one arrow to shots you are making while also completing combo shots during missions can also trigger it... in other words, when you are doing cool stuff... but don't quote me on that one... unless it's confirmed .
The only fixed way to get one is via hitting 90 Tie Fighters.