Revealing mistake: When Tommy Ross gets killed and Carrie looks at his supposedly lifeless body if you look closely you will notice he blinks revealing that he is actually alive.
Revealing mistake: In one shot when the boat is pulling away from the waterfall, you can clearly see that the shot is the same one they used earlier in the movie. The water from the waterfall now is going up the cliff! They have just put it in reverse.
Revealing mistake: When Louis gives Gage the lethal injection, because the syringe is transparent you can actually see the prop needle retract in and out of the syringe as he supposedly injects Gage.
Revealing mistake: When Dracula flies into the room to stop his brides from devouring Jonathan, the board carrying him is visible. (00:34:10)
Revealing mistake: In some extended edition cuts of the film, Regan backwards spider walks down a flight of stairs, and blood falls from her mouth. But her face isn't that of Linda Blair, but of a stunt double.
Revealing mistake: When Glenda is killing the mother in the shower towards the beginning of the movie the mother's underwear is visible through the shower curtain.
Revealing mistake: After Steven Wilkins disguised as a vampire kills the unnamed woman he closes her eyelids to make it look like she's asleep. Just before his hand contacts her eyelids you see her almost blink, revealing she's very much alive.
Revealing mistake: In the scene when the main character is in the library on the internet, she goes to a couple of websites. When the shot shows the URL up top, it is C:\windows98\mydocuments\etc.html. Instead of actually searching on the web they used a premade html page and accessed it from their computer.
Revealing mistake: Right after Nell sends Hugh to hell, Dr. Marrow and Theo come out of hiding behind a pillar. As Marrow puts his hand on the pillar, it squishes in as if it was made of foam rubber, instead of stone. (01:39:50)
Revealing mistake: Before Paxton is hit with the 3 prong instrument, you can see the bloody holes already on his shirt. (01:01:20)
Revealing mistake: When the kids are burying Gus, his supposedly dead face flinches when they shovel dirt on him.
Revealing mistake: When Wolf Jackson touches a headstone as he and the police are about to raid the church, you can see the headstone wobble when his hand lightly touches it, revealing it to be made of a soft, perhaps Styrofoam-like material and not a real headstone.
Revealing mistake: When the UFO makes the huge flash that knocks everyone in the cemetery down, one of the police officers kicks a tombstone as he falls and it wobbles back and forth. (00:13:35)
Revealing mistake: When Nica crawls to the elevator to escape Chucky, she bends her legs in order to shut the elevator door. She is meant to be a paraplegic and have no feeling in her legs.
Revealing mistake: When the team descends to the bottom of a hole and one female member is first wounded and then dies. After checking her pulse, the others pronounce her dead and begin moving out. As the last one is leaving, the "dead" actress lifts her head up off the ground and looks left. (01:13:10)
Revealing mistake: When Brom (disguised as the horseman) throws the jack-o-lantern at Ichabod, there is a shot from Ichabod's perspective showing the jack-o-lantern flying toward him. It jiggles from side to side, revealing it was travelling on a wire.
Revealing mistake: As Drew Barrymore is running from the killer outside he stabs her. If you look closely it is very easy to tell it is a rubber knife, because you see it bend off of her. (00:10:20)
Revealing mistake: When Henry's mom is pushed off the cliff her cable is visible.
Revealing mistake: Throughout the film, the base station radio is not connected to an antenna. In many lengthy shots of the back of the radio we can see the power cord trailing out the back of the unit, but there is nothing plugged in to the antenna socket. This is especially annoying because base station radio problems are a key plot point.
Revealing mistake: After the hitch-hiker cuts his hand and hands it to Franklin, the blood disappears from the knife, meaning the knife was switched between cuts.