Błędnie: Does she have something in her mind? She looks worried.
Poprawnie: Does she have something on her mind? She looks worried.
"To have something on one's mind" oznacza 'martwić się czymś', 'mieć coś na głowie' (kłopot, zmartwienie). "To have something in mind" oznacza 'planować', 'mieć zamiar', 'mieć coś na myśli'.