It's all a bit tricky as we weren't there. I think the critical points are:
1. The umpire is supposed to "call and signal no ball".
2. You can be run out off a no ball.
3. Had the batsmen crossed as they were going for a run, and mistakenly thought that the striker was caught out?
4. If the striker thought he was caught, was he meandering after crossing because he incorrectly assumed he was out?
If the situation is point 4, and the umpire hadn't called "No ball", then it should be declared "dead ball" and the innings should resume with no run given and the batsmen returning to their ends.
That would really be in the best spirit of the game.