In the movie when Mia rides in the limousine for the first time, it shows a glimpse of her from the back as they are approaching an intersection. You can see on the side of the road that there is a stop sign, but Jo, the driver, just keeps on driving. OOPS
I laugh everytime I see that part! I don't think it's a slipup because Joe mentions that it's because of the flags he can park anywhere, so maybe he can run stop signs because of the flags too! Or maybe he was just getting accustomed to those "California stops" we have over here: no one's coming? Just roll through...
When they are in the limo there are cops and when you hear sirens you are supposed to pull over so when they approach the intersection the sirens from the cops stop people from going through the intersection, so joe can go through as he pleases.