When the girl is sitting in the car and her boyfriend leans in to talk to her, he gets stabbed in the face. Her face is sprayed with blood but a few seconds later her face is a lot cleaner. This is about at the twenty minute mark.
When the girl reaches for the cell phone after her boyfriend is killed, she gets stabbed in the hand. Before she gets stabbed her hand is over the phone. When she gets stabbed, the phone is no longer there.
When the girl is locked in the bad guy's car after he locks it by remote somehow, the doors are shown unlocked several times while she is honking for help and also just seconds before the bad guy unlocks them by remote to get her.
(at around 1 min) The girl sitting in the car with her boyfriend tries to read the license plate off of Chrome Skull's car. The black car used here in a Chrysler 300 SRT8 due to its bigger 20" wheels, mesh grill, and SRT8 badge. However, the rest of the movie uses a black Chrysler 300 Touring with the smaller 17" wheels and honeycomb grill as Chrome Skull's car.
At 54 minutes into the film the survivors retrieve the cellphone that belongs to the killer. They try to call 911 but can't because the phone is locked and password protected. All cellphones even if locked can still call out to 911. It is the only feature that remains unlocked.
When the girl is calling 911 and she pulls the handset cord out of the base of the phone while they are trying to trace her location, she is disconnected and they don't complete the trace. This type of phone has the "receiver" switch on the base and does not disconnect when the handset is detached. The receiver switch/lever has to be pressed down to disconnect the call.
The goof item below may give away important plot points.
When the girl finally smashes the villain, her tank-top is soaked with blood and is more than eighty percent covered, as is her face. When she leave the building, her shirt has only a few splatters of blood, and her face is completely clean.