Continuity mistake: When the back of the Fratelli's ORV is riddled with bullet holes, you can see they make a distinctive backwards "L" shape above the Jeep letters. Later, when Chunk examines the ORV, the bullets holes are now in different places than they were before. Also, the license plate that is seen on the ORV when it is hit by the bullets, changes design as well. (00:02:45 - 00:30:30)
Continuity mistake: When Data activates his 'slick shoes' on the log bridge, the heels of the shoes pop open to reveal the 'slick shoes' mechanism which starts spraying oil. In the next shot though, they show Data walking across the log, the heels of the shoes are closed, and the oil squirts out of holes in the back of the heels apparently.
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.
Continuity mistake: All the Goonies get soaked while in the Old Moss Garden wishing well, but when they are seen again in another part of the cave they are all dry, and there is not a sign of being soaked.
Other mistake: In the shot of the old guys taking a shower, you can see the outlines of the tiles that are supposed to be smashed when the water regulators withdraw into the wall. (00:50:50)
Audio problem: When they are standing in Mikey's kitchen looking at the map, all you can see is their eyes above the top of the map. Right before it cuts away to the Cyndi Lauper video, the map moves down just enough to see Chunk saying something, but there is no accompanying audio. (00:22:40)
Continuity mistake: Right after Troy is humiliated at the wishing well, the movie cuts to a television food program, with Sloth's reflection visible in it. The problem is that Sloth's face is noticeably different in this reflection than the rest of the film. For instance, his left eye is only a bit lower than his right eye now, instead of it being considerably lower like it usually is.
Continuity mistake: When Mikey takes the skull necklace off Chester Copperpot, he accidentally pulls Chester's skull off his body. When Mikey does this, the skull is still touching the body, just detached and at the wrong angle. But the next shot we see with the skull, when Brand goes to place the skull back on the body, the skull is about a foot away from the body.
Other mistake: When Data puts his tape in the stereo he shuts the thing then the 007 music plays. He doesn't ever push play.
Continuity mistake: During the high speed police pursuit behind the Fratellis, once the second police cruiser pulls behind the first, the squad cars' positions change - in some shots the second police cruiser leads and in some shots the first, just note the different bumpers. (00:02:30)
Continuity mistake: The design on the face of the treasure map and its two holes change, from the scene where the Goonies are in the attic to when they are downstairs again (i.e. it has a red stripe across it at first sight that disappears). (00:16:35 - 00:22:25)
Continuity mistake: In the shot of the Goonies running to the attic upstairs, you can plainly see that it is not raining or stormy outside. When they enter the attic (barely seconds later), it's already raining outside along with the thunder and lightning. (00:13:40)