Hard to forge?
"Arriva tells us that the combination of a clock ticking away, along with animated Arriva symbols, would make the ticket hard to forge, and that drivers would be advised of that day's colour (orange in the example, top right) to make things harder for the would-be forger."
Java apps are trival to reverse engineer, so your ticking clock and and animated arriva symbols are absolutely not hard to forge. In fact, you wouldn't even have to forge them, just modify their app.
As for the colour... well, that just sound impossible to work around!
I mean, good god, a simple, low-tech solution doesn't mean it has to be full of gaping security holes.
They might as well just use a lie detector and ask the passenger if they've bought a ticket.