About this scene
Pharmacy counter, morning, two staff visible behind the dispensing window. She's mid-sixties, in a beige cardigan, glasses pushed down to the end of her nose. She's digging through her handbag for her wallet, item by item, completely focused on finding it. He flashes at the angle she'd see if she looked up. She finds the wallet, lifts her head to count out cash, and her hand stops with two bills sticking out. The thing she was about to say to the cashier evaporates.
What to watch for
The bag-rummage is the setup. She's been digging for almost forty seconds when the flash happens. She does not see it during the digging. The reveal is the head-lift. Watch the bills in her hand. They drop to the counter when she registers the angle. She does not pick them back up. The cashier waits politely. The cashier eventually has to say her name. She blinks twice, picks up the bills, and pays without looking at her change.