About this scene
Pedestrian sidewalk, afternoon, midblock. She's walking toward him at normal speed. The flash is bold, fully out, and her line of sight catches it from twenty feet away. Her face goes through the full delayed reaction. Recognition takes about half a second longer than it should, like her brain needs to verify the input before committing to a response. The reaction lands hard and you can see her actively try to put her face back together while still walking.
What to watch for
The delayed processing is the comedy. Most reactions are immediate. Hers has a clear lag, almost like she's translating the visual into a language her face can use. By the time her expression has caught up to what she's seeing she's already past him by ten feet. She turns back once. Her face is still working through it. Then she turns forward and walks at slightly faster pace for the next block before she pulls out her phone to text someone.