I think the tickets had to be activated 'online', and iirc they are good for 60 minutes. Additionally the color bar screen has an animated timestamp too, presu

I think the tickets had to be activated 'online', and iirc they are good for 60 minutes. Additionally the color bar screen has an animated timestamp too, presumably to prevent a (basic) screenshot attack. And; although I've never had it scanned, I think if the ticket checker suspects something is up, they scan the qrcode for an online verification. I took a large family group with me on one ride, and they did consistently check that I activated the right number of tickets.