When the four are on the island, both girls are wearing bathing suits under their shirt. When Alex is in the hospital, she's seen wearing a black bra.
Near the end when talking to the officer in the hospital a phone is seen in a evidence bag and when the camera cuts to the office the phone is on top of the bag.
When the four actors are getting out of the helicopter, the scene shows the chopper blades going full speed, but if you look at the actors hair and the grass, it is not reacting to the wind that would be caused by the moving chopper blades.
Lex's backpack is constantly changing from being on her back to not being on her back when she is supposed to have it, then it magically appears again.
There appears to be no electricity available in the resort, yet Lex is able to operate the lift.