Revealing mistake: When walking across a curved path, you can see Judy step off the floor where he was supposed to walk.
Revealing mistake: When Gypsy tries to hit Helen with her weapon, she misses and hits a table instead, causing one of its leg to break off. However before the weapon even hits the table you can see the leg coming off from the table; obviously being pulled off.
Revealing mistake: Near the end of the DVD version, one of the main characters (I think Deke) is chainsawing the spiders. In two of the shots, you can see the man's legs through the spider.
Revealing mistake: When Rolfe is walking down the hallway to Sally's apartment, there is an orb where the hallway is lighter colored and his legs seem to jump and undulate due to the special effect used to hide the fact that the actor is actually full-sized, walking on his knees.
Revealing mistake: The first night Ben brings Andie home, he starts the music on the CD player, but no CDs are spinning at all. Yet, the music still plays. He also changes the track mid-scene, and still no CD is spinning.
Revealing mistake: When Otis cuts off Bill's hand, you can see it's a fake hand because it turns sideways after the first swing of the axe.
Revealing mistake: When the cannibal throws Francine on the floor, you can see her pulse in her neck.
Revealing mistake: We get a close up of the article in the morning paper with the headline "L.A Cops Indicted" however the article's text is about a possible curfew for teenagers. (00:04:30)
Revealing mistake: One of the accountants' computers has no power cord attached to it.
Revealing mistake: Jack is lying on the couch (whoever managed to fetch him back from the nest is anyone's guess) with an alien tentacle up his nose. The special effect used to display the invading organism swelling his brains is an obvious image morph that does not look in any way plausible visually alone - let's not even consider the glaring anatomical issues. (00:39:55)
Revealing mistake: When Kirk Douglas returns from his run in the park the door attendant calls him "Mr. Douglas" and then corrects himself in the next sentence after Kirk waves him off.
Revealing mistake: When Hulk rips the turret off the tank and swings it around in the desert has a solid base. This is correct for a model but not for a real tank which has a hollow turret for the tank captain to stand up from the bottom of the tank through the turret and look out the top.
Revealing mistake: When Tara Reid is being slapped around, pushed and tossed out of the cabin, we can see that it's a stunt double, by the dark hair at the front where the white wig has slipped back, exposing the double's dark hair.