You'll not see one flagging. In Super League, they'll use comms. In the Championships they might use comms or the forward pass signal (if the ref looks at them) which is the flag held vertically on the chest.

What if the ball is passed backwards but the receiver is in front of the passer but still takes the ball cleanly whilst reaching back?

As I said previously Ganson had an unobstructed view but he was just being Ganson as always.

There were LOADS of forward passes pulled in Carcassonne, every one that was a bit flat was given.

The referee was very letter of the law.

He seemed about as popular with the French crowd as Jamie Le Ahy is

See earlier response. That situation's going to be a lot less than 1%, isn't it ? Like about 99% less.