Factual error: The teens are traveling presumably along the Meadowbrook or Wantagh parkways, when they enter Jones Beach. They see a sign just before the beach entrance that says "New York: 93 miles", when Jones Beach is less than 15 miles from NYC limits and approximately 25-30 miles from Manhattan.
Factual error: The flight attendants didn't do the safety briefing properly. None of the flight attendants show the demonstrations. Also, the safety briefing should be given during taxiing to the runway. But in the movie, the flight attendant had finished the safety briefing before the door of the plane closed. During the safety briefing, the flight attendant said that the aircraft has 6 emergency exits. How come a 747 has only 6 exits? A 747 in fact has 5 main deck exits on each side, which means on the main deck there are 10 exits. Judging by the picture of the plane on the DVD inner cover (New Line Platinum Series), the 747 used in the movie most likely is the 747-200 series, which means the upper deck has one emergency exits. All in makes the plane has 11 exits, almost double the number said by the flight attendant. And during the take off, when Alex looks outside the plane to the wing, he sees that the flaps are just being deployed. When a plane is taking off, the pilot needs to make sure that the flaps are deployed BEFORE they are actually on the runway. (00:10:05 - 00:17:00)
Factual error: Later in the movie when Mrs. Lewton is playing John Denver's Greatest Hits, there's two things wrong with the scene: Rocky Mountain High plays as track 1, but is not the first track on that album; second, the song is out of order. The line "but the string's already broken, but he doesn't really care" is repeated twice before her death.
Factual error: When the teacher gets killed, the vodka on the floor catches fire, and there's still enough alcohol left that the fire follows her? I don't think so - vodka will burn, but not that well.