Revealing mistake: When the guy that was shot in the chopper is falling, you can see the protective, yet flaming mask on his face.
Revealing mistake: Charlie is underwater and flashing back to when she was in the trunk of the car, the camera cuts to her face and the air bubble is going into her mouth, not coming out.
Revealing mistake: Near the end, Timothy came out of the hotel, after the explosion, without a scratch.
Revealing mistake: In the time it takes to run to the pond, and at the speed the people are driving. Charlie couldn't have run, put on, and laced up her skates.
Revealing mistake: When the guys jump Charlie and Mitch in the alleyway, a gunfight ensues. However, after the last bad guy is dispatched and a total of a dozen gun shots have been heard, if you look at the street behind them the people are still walking calmly as if nothing happened.
Answer: According to IMDB, the final scene was filmed at Figueroa Mountain Farmhouse, Los Olivos, Santa Barbara County, California.