Olivia Wilde's first day of shooting was actually the scenes where her character almost freezes to death and she was only in a miniskirt during filming in Canada.
At Bobby's hunting cabin, when Addison listens to Liza's voicemail he has one stream of blood running down his forehead. When he turns around to write down an address, he has an extra stream of blood running down his cheek. And when he turns back around the stream is gone.
During the opening sequence, the get-away car hits a deer, smashing the windshield and covering it with blood. In the following shots showing the car careening out of control, the windshield is intact with no damage.