There's a moment almost close to the end when Becky is sitting and starts watching the monitors with the security cameras footage. It seemed like she realized something, but I don't remember if it was shown what that was...
I'll be good I swear... I'll never see a movie ever again.
Realized that the cameras had been on her when she'd been out front taking orders, and she had proof that she hadn't stolen anything. Possibly also realized that a real cop would have asked to review the security footage before making an accusation. And perhaps furthermore that there was a camera in the office, and everything from the strip search to the blowjob had also been filmed.
That's why this never would have happened at the Wendy's where I used to work. The owner took the security cameras very seriously, and made sure his managers did too. Someone *was* caught pilfering, and someone else taking money out of the register. If "Officer Daniels" had called that store, he would have been told, "I'll check the security video and get back to you." (Plus which, it was literally next door to a police station, and we knew all the cops...)