One other thing, if it was a terrorist group and things went wrong, then why not take credit for the kill?

You keep quite if you are not done yet.

It could be a dry run, but if there were terrorists on the plane it was a dry run where they died in the end (assuming the plane did not land somewhere) then I would have to question what type of terrorist would go in for that?

I have to be careful, because I am the first to argue that trying to impute logical motives to terrorists activities is probably not your best option. You have to think like them. But even they would not be willing to kill off a fellow terrorist unless there was gain in it somewhere.

Time traveling, mango eating space aliens - got to be the answer.