Revealing mistake: The cool hi-tech roulette table has trapdoors and a rolling surface and...no it does not. None of that is real, it's all poor CGI. (00:19:00)
Audio problem: When the mysterious lens flare creature possesses the microwave oven, its door opens with a disproportionate "creaking door hinges" sound effect. Inherent phoniness aside, the noise is also continuous, but if you look at the door, it did not open in one fluid motion; the actor's pelvic thrusts as he was boinking the stewardess got in the door's path for a moment putting it to a momentary halt. (00:14:05)
Continuity mistake: Janet the stewardess is bending over to do some kitchen work, and a guy who was passing by gets all frisky about that. He has his hat in his right hand, but going through the door to act like a caveman (much to her delight, too) his hat switched to the left hand. (00:11:20)
Other mistake: When the pilot reaches the plane, the car 'slides' in front of the background in an obvious fake movement. Not that a pilot would drive his car and park it on the airport lane a few yards from its wheels anyway...in between two engines of a jumbo jet even. (00:04:50)
Revealing mistake: When the protagonist drives through Las Vegas and then to the airport, all the reflections in his car window are tacked-on post-production effects (obvious lens flare, images superimposed on the frame, etc). (00:03:50)
Continuity mistake: The pilot wakes up in a cold sweat and (without a change of clothes) starts putting on some pants and shaving. As he shaves, he puts on in close-up his shoes. Not only the shoes were nowhere to be seen (and the razor is on a short cord) but now he has socks too. (00:02:45)
Character mistake: The very advanced computer on the plane can't spell, since it infers probabilities that a member of the crew has been "INFECTETED" by the creature. (01:06:40)
Other mistake: Everything is lost, or so it seems when a fuel leak is discovered. Carol the stewardess sobs because it was her last flight, and she was just 3 days away from her wedding. That's nice, too bad that it was the background story of the OTHER stewardess, Janet, as established when she was boinking Bob. (00:12:00 - 01:15:00)
Other mistake: Mike sabotages the parachutes...of which there are exactly four, like the number of survivors. A bit scarce for a Boeing with a staff alone double that size.
Other mistake: Pat faints on the green, blocking the shot of the rich patron. Since the curtains were open and the group of four people was facing the entrance, which is right by the golf hole, it's impossible that nobody saw her slowly stagger her way to the green, nor heard her wheeze. (01:02:40)
Other mistake: Jack's eye pops out in a spurt of blood; besides the phony CGI effect, he manages to spray with blood the part of the glasses that faces the camera (the same direction he is facing) and not the side that faces him. Moreover, lengthy blood drips appear on his cheek only at the cut, absent in the first shot. (00:56:45)
Other mistake: The virtual chess game ends with the queen taking the other queen and then the king as the word "Checkmate" flashes. Ignoring the fact that technically the king is never taken even when checkmate is declared (many videogames add flamboyant animations), it still was not a checkmate. The king in B1 had C1 to go to, it is not under threat. (00:50:55)
Other mistake: The surviving lady is looking for Don who just killed Mike. There's a POV shot that pans from the dead Janet to the end of the room; it is obviously meant to be Rosie Malin's, but the effects used are the alien POV's, and she is not possessed (just yet). (01:18:30)
