Continuity mistake: Troy is the first passenger to exit the plane, yet in the next shot he is spotted walking down the stairs behind Neville Flynn. It's easy to spot him by his orange shirt.
Continuity mistake: When the couple honeymooning die, the man gets sprayed by venom in the eyes, and begins foaming from his face in the close-up shot. However, when the camera cuts to a wider angle shot, the foam suddenly disappears.
Continuity mistake: When the snake attacks Sean at the end of the film and Flynn shoots him and the snake, the snake disappears completely.
Continuity mistake: There are times when the interior of the plane is plunged into complete darkness for long periods, yet all exterior shots of the plane show the interior lights on.
Continuity mistake: Early in the movie, officer Brown is saying goodbye to his two kids on the plane. His hand moves from the inside to the outside of his pocket several times between shots.
Answer: Rattlesnakes only make a noise when they are disturbed and some rattlesnakes will even strike without starting to rattle first.
Myridon