When the limo goes off the bridge, it lands upside down in the river. It's also upside down in the next season's premiere when it's hoisted out of the water by a crane. But it appears to be right-side-up in other shots when the inside is shown underwater. As the car is sinking, its unconscious passengers are shown sitting right-side-up. When Nathan swims in and gets trapped he is also right-side-up; the closed moon-roof is clearly visible above his head as he's yelling for help.
Haley tells Lucas that everyone got ready in the same room,' even Rachel and Brooke for some reason.' Brooke is Haley's Maid of Honor, so it makes sense that she would get ready with everyone.