When Ruby is signing on to AOL to check her e-mail, the modem can be heard dialing and connecting before she actually clicks the 'sign on' button.
In the final sequence, the make and year of police car changes twice. It starts out as a Caprice, becomes a '93-97 Ford Crown Victoria, then changes into a '98-01 model of the same car.
Ruby crashes her car into a gate. In the next scene, the gate is clearly intact.
After Ruby's late night swim, she is seen hugging her torso, but the next shot from behind her shows her hugging her shoulders and the following shot is back to her torso before she moves her hands up to hug her shoulders.
When Ruby is stealing Terry's car she starts the motor in the garage. When they show the dash and gauges the oil pressure is at zero and the warning light is on. Again when she is driving the car and her brother is changing the radio station the dash is shown again and the oil pressure is still at zero.
Three of Ruby's high school friends complain that Ruby has not been returning their e-mails - this is after we see Ruby discovering her AOL account has been terminated. In this case, her friends' e-mails would have bounced back, possibly alerting them that something was amiss.
When Rhett and Ruby are in the back of the police car, Ruby jumps into the front seat after Terry emerges. This is impossible considering every police car has a barrier separating the back seat from the front seat to protect the officer from prisoners in the backseat.
Ruby's iBook is not connected to a phone line. She could have been using a wireless network (AirPort), but there would be no dial tone (see above) even when the AirPort base station was dialing up.
When Ruby walks into the house after going out to dinner with Terry, she crosses the kitchen into the room where Erin was injecting herself. When she passes through the kitchen, there are two very clear faces, most likely crew members, reflected in the glass.
When Ruby gets out of the car after Terry touches her shoulder, the crane supporting the moonlight is visible.
When Terry Glass drives out to find drugs to take care of Ruby the drive thru gate is fixed. Terry owes $1,000,000 plus well over $30,000 in interest to loan sharks, however he spends at least a couple of thousand dollars on fixing the gate Ruby destroyed earlier.
When Nancy Ryan opens the medicine cabinet, she finds two bottles of insulin. Insulin must be kept in the refrigerator.