Revealing mistake: After Mary Robert jumps out of the car, you can see the stunt double falling for her.
Revealing mistake: In the part it shows Ash getting sucked into the time portal you can see the wire he is hanging from. (00:02:45)
Revealing mistake: There is an obvious stunt double for Grandpa during the fight scenes.
Revealing mistake: When Tim Curry runs out of Kevin's hotel room after being scared by the inflatable clown doll he hits his knee on a table. When he hits the table and then hops away you can clearly see that he is wearing a knee-pad.
Revealing mistake: During the ghost of Christmas present, Kermit is walking with tiny Tim on his shoulder and you can tell Kermit is walking on a spinning drum. Right before the camera pans away you can see Kermit's feet slide like he stopped walking but the road kept spinning. (00:55:00)
Revealing mistake: When George Newton comes into the house and it is raining he has an umbrella in his hand. If you look outside his door underneath the balcony it's wet, but further down the path the ground is dry.
Revealing mistake: While Nick and his father are driving home with the giant baby behind (an obvious green screen projection), the baby breaks a tube from the car and throws it to the floor. Nick bends down to pick up a prop located offscreen, to add up for realism, but the problem is that he bends down before the baby throws it, so the whole trick is revealed.
Revealing mistake: The film is supposed to be in Alabama, but it was actually shot in Georgia. You can see this when Vinny and Mona are first pulling into the town and they are turning left, in the shot you can see the Georgia State Highway road signs off in the distance. (00:13:20)
Revealing mistake: Near the beginning when they are in the pool and the first earthquake hits. You can see a board covered in soil lift up, which the dog is on.
Revealing mistake: In the chase scene about an hour into the movie, Robert Loggia is shown entering the Liberty Tunnel, driving on a wet road. Note the vaulted round ceiling of the tunnel. Next, we see a series of shots of him in the tunnel, and then a shot of the sun rising over Pittsburgh as he is about to leave the tunnel. Here is the problem - the sunrise shot is taken from the Fort Pitt tunnel on a different day. Note the dry road, the barriers to the driver's left at the tunnel exit and the Fort Pitt bridge straight ahead. There is no place for the driver to make a left turn out of this tunnel. Also note that the POV is from the left lane. All the Liberty Tunnel shots show Loggia in the right lane. The next shot shows Loggia exiting the Liberty Tunnel and making a left turn from the right lane, causing a pile-up. (01:11:10 - 01:12:20)
Revealing mistake: As the three zombies go rabid at the house party, and McGruder and Thug tear the skin off a guy's face, the switch from actor to dummy is visible. (01:10:55)
Revealing mistake: When Ernest runs away from Lisle, after he nearly drinks the live-forever potion, he runs down a hallway and commences to open a door with a doorknob on the left side of the door. It then cuts to the other side of the door, of Ernest walking through the door (into the party), and now the doorknob is also on the left side of the door, but it should be on the right side. (01:21:35)
Revealing mistake: In the scene at the church, immediately after the girls were at the Suds Bucket, Mae is in the confessional when the priest drops his Bible. Mae steps out and kneels to pray as the priest opens the door to see who has just made their confessions. A closeup of the priest's face reveals that he has a "cowlick" (several locks of hair) hanging down in the middle of his forehead, but in the very next shot showing him in the background looking down at Mae, the lock of hair is suddenly gone.
Revealing mistake: When Nick returns to his apartment (after being made invisible) he immediately closes the curtains. Although he is invisible, we should see the curtains pulled closed at the point that he grabs them with his hands. Instead we see them close from the top, revealing they were closed either by a crewman or an automated process. Note: The curtains are NOT meant to be automatic in the film as we see and hear him physically close them.
Revealing mistake: In the scene when Roy returns to rescue Helen, he runs into Spike and then gets shot by him in the chest. When Spike checks Roy, he finds that the remote in his shirt pocket stopped the bullet. However, there isn't a hole in the shirt pocket.
Revealing mistake: When Bob Roberts falls off his motorbike, if you watch closely after he falls he gets up and faces to his right before the camera pans away. When the camera pans back a few seconds later, he's lying down again. It's obvious that the stuntman and Tim Robbins switched during this time, each hiding behind the parked car. (00:49:40)
Revealing mistake: When Daniel belly-lands his plane the rotors get totally bent. When the plane bounces back the rotors happily rotate again, revealing their rubbery consistency. (00:03:15)
Revealing mistake: In the ending when they are pulling into Miami you can see the exhaust from the engine even though it is supposed to be seized. (01:34:30)
Revealing mistake: Newton is in his car driving to stop Gwen from leaving on the bus, he cuts the corner and drives over the grass. You can see where the car has drove over the grass and road on previous takes. (01:30:55)
Revealing mistake: Toward the end of the film, there's a scene were Dick hits a Spango soldier and Dick shakes his hand in pain. If you look over his right shoulder, you see two people fighting but there's no physical contact being made.