Who gave Dereck the order to kill Andy, Derek's friend in the future who told Derek that he created Skynet? Did they make a pact that if either of them got the chance to go back in time they would try to stop Judgement Day by killing Andy?
How did Jesse get to travel back in time? Who were her co-conspiritors and did anyone other than Riley come back with her?
Why didn't Sarah tell Derek that John Killed the Mercenary leader who captured her and John and blew up Cameron in the first episode of this season. Why did she want Derek to think that John was tramatised because he saw her kill this guy? When, in fact, John was traumatised because he killed the guy himself with his bare hands.
Why did Vick (the terminator that killed Derek's other resistance members) classify Cameron (on his internal analysis screen) as an unknown terminator model.
What happened to Derek when he was taken to the basement to be interrogated by the terminators in the future scene where he met Andy? Piano music was playing as Derek walked in. The scene ended with a shot of Cameron at a piano.
Why did Cromati think agent Ellison would lead him to the Connors?
As the story has moved on from these characters, Derek, Jesse, Cromati, Andy, we probably will never find out the answers to these questions. I think some of them would have made far more interesting scenes or sub-plots than the main stories told in episodes like 'The Good Wound', ' Some Must Watch..' and 'Desert Cantos'. Those episodes were 'series killers'.