Silent Hill was... not a good movie...

[Weltall]

Riiight. The reality is that despite what they INTENDED for that scene to mean, it came out as ridiculous. No one in the audience understood the reasons for that sudden "I'd better go!" thing. She had no reason at all to think she would be arrested, she barely had reason to think she might get a ticket, and was the risk of actually being PUT in jail and losing her child really worth a, at the MOST, half hour delay? All it ended up doing was crippling her in that town anyway, when otherwise she might have had an ally give her a gun early on, perhaps in some coffee shop.

She had damn good reason to think she could be arrested. She took her daughter against her husband's wishes and without telling him. For all she knew, Christopher could have told the police that she kidnapped her daughter and was taking her to Silent Hill. He didn't do that, but it's hardly a stretch to believe he might considering the circumstances (he did take other measures to stop her, such as cancelling her credit cards), and considering that Rose had a terse, uncomfortable exchange with a nosy cop poking around her car, one could certainly think Rose had that thought in her mind when Cybil pulled her over.