Revealing mistake: When Nancy is running up the stairs in her house to escape Freddy for the first time her foot hits the steps and go through the steps into some goop. Look at the steps above that step and you can see the pre-cut holes where the next sets of goop will be. (00:39:10)
Revealing mistake: When the TVs explode, the glass is very fake and "cardboardy".
Revealing mistake: When the professor is trying to find the gremlin, he is in the room with the movie playing. The projector that is playing the movie is actually moving backwards. (00:44:35 - 00:47:35)
Revealing mistake: There are two Ewoks Wicket's parent is in search of. One of the those Ewoks is climbing down a mountain and the other has finished climbing down. As this happens, look at the Ewok not climbing. As he bends down, half way down his left leg, there is some sort of fold there. This is mainly due to the fact that the Ewok actors wore costumes whilst filming. The fold is coming from the Ewok costume. (00:07:50)
Revealing mistake: Conan and his party flee from the temple guards and escape into the crypt, closing the huge stone door behind them. A moment later, the camera shows the leader (Ferdinand Mayne) standing at the foot of the steps holding a torch. He chucks the torch out of sight to his right and begins walking towards the door. If you look closely you'll see the torch disappear nicely out of sight behind the wall as if he had "passed" it to someone standing there.
Revealing mistake: During the invasion of Dune by the Harkonnen, a Sardukar soldier throws a guard from what appears to be the palace's wall. When he hits the ground all the bodies around him bounce as if they where lying on some sort of cushion. (01:09:50)
Revealing mistake: When the guy on the horse pulls out his sword, he has trouble getting it out of the sheath at first and it bends severely. It is clear that it is not a real sword.
Revealing mistake: Watch very closely when the horse is waking up Atreyu. It seems to be searching for something behind Atreyu and then you see a sugar cube fall out from behind him.
Revealing mistake: When Supergirl flies through the window to fight the invisible monster, half of the screen shows her jumping in a school uniform and the other half exiting with the Supergirl outfit. Watch closely and you'll notice that her halves don't match, giving the sense that she is missing part of her body.
Revealing mistake: Going to his father's old place, David and Allison turn right on the corner, pass some stores and then turn left to drive into the lot of the Texaco station. The reflection shown in the stores' windows across the street is not at all what is supposedly across from those stores. Also, when they start to pull away from the station a set of studio lights are reflected in the side back window of the car. (01:02:40)
Revealing mistake: When Roger is in the bathroom at the urinal, he can see Edwina's reflection in the mirror (as she is, supposedly, inhabiting his body). However, when Roger lets out a particularly big exhale, Edwina's bangs blow slightly upwards, showing that the "mirror" effect is achieved by simply having her stand behind a wall right in front of him. (00:29:45)
Revealing mistake: As Vicky and Burt are driving down a dirty lane, through a row of corn, you can see fresh tire tracks in the mud from a previous take. (00:34:35)
Revealing mistake: When Bob Cratchit takes Tiny Tim by the town square to watch the boys play, you see many boys "sliding" on the ice. In the close-ups of the boys you can see the "ice" ripple beneath their feet, revealing it to be some sort of plastic.
Revealing mistake: Clearly a mannequin when Countess Zanda falls out of the helicopter.
Revealing mistake: When Christine escapes from the window, she turns into an athletic guy. (01:10:45)