[paulgb]

> You can go to the kiosk at any BART station and the station attendant will put a sticker on your card to indicate that you are leaving via the same station you entered and allow you to exit via the emergency doors, therefore not incurring the excursion fare.

What if you use the phone app and don't have a physical card with you?

[CoffeeOnWrite]

The sticker is just a plain sticker. I would assume they'd let you put it on an alternate surface..

[clintonb]

The sticker doesn’t matter. The phone maintains an open “transaction until you swipe it at your destination. It’s not clear what happens if you leave the the station without swiping, and return a few hours/days later. I suspect they still charge you for the excursion fare, or a higher amount.