Revealing mistake: In the scene in the cave where Brand pulls back the rock and the bats fly out, there is a close-up of Mouth with bats flying in front of his face. You can clearly see the wires attached to the bats.
Revealing mistake: When all of the Goonie kids run upstairs to the attic, they rush past the camera, and you can see the image wobble slightly, as if one of them jostled the cameraman.
Revealing mistake: When Chunk opens the freezer in the Fratelli hideout to get the ice cream, if you look closely at the old dead man he moves his eyes several times between standing upright and falling over, and when he and Chunk are in the freezer together.
Revealing mistake: As the dead guy falls out the freezer, he is seen blinking.
Revealing mistake: When Brand moves the rock and hundreds of bats fly, note that the blatant fake rock has a chunk of painting missing, revealing the white material underneath.
Revealing mistake: When the bats escape from the fireplace, it's obvious they are just black pieces of material.
Revealing mistake: When the floor crumbles from under Mouth we see a shot looking up from the pit to him leaning back trying to keep his balance. If you look closely you can see him kneeling on the ground helping him to lean back further.
Revealing mistake: When Francis Fratelli is trying to pick up the gun as the Goonies are escaping from the organ, you can see the rocks shaking each time he drops the gun on the ground.
Answer: He says, "He is a big strong man."