(at around 1h 8 mins) When Sloth breaks his chains to release himself, he rips them out of the wall. However, you can see from how he is chained that he is not only chained to the wall, but his hands are cuffed together. He does nothing to break the cuffs on his wrists yet when he rips the chains from the wall, the cuffs disappear.
(at around 1h 20 mins) When Andy makes the first mistake on the bone piano, a huge hole appears and Mouth almost falls in. When she makes the second mistake, another hole appears and Brandon almost falls in, but the first hole has gone, and only reappears when the puzzle is solved.
(at around 40 mins) When Chunk is drinking out of the cooler it is almost empty but when he hits it and grabs it to try to keep it from falling it is more than half full.
(at around 1h 30 mins) When the kids are jumping off the pirate ship, Data jumps off twice.
(at around 46 mins) While going down to enter the cave, Data's shoes are white with a black Nike sign. In the next shot he is wearing black shoes and a white Nike sign.
(at around 1h 12 mins) When Chunk is on the phone with the sheriff and Sloth pulls out the cord that connects the receiver to the phone, a dial tone is heard on the sheriff's end. Unplugging that cord wouldn't have disconnected the call.
(at around 49 mins) When Chunk escapes from the Fratellis and arrives to a car, Chunk can't see who is driving but in real life you should be able to make out the face from that angle.
(at around 24 mins) When Brand starts to go after the rest of the Goonies on his bike, Mrs. Walsh says that if he was not back with the rest, she would commit 'Hari-Krishna', after which Brand (incorrectly) corrects by saying, "It's hari-kari, mom." The actual Japanese term is 'hara-kiri', although 'kari-kari' is a common mispronunciation, especially among Anglophones.
(at around 1h 45 mins) At the end of the movie, Data tells the news reporters that the "octopus was really scary". This actually refers to a deleted scene, but there's nothing to indicate that he wouldn't just make stuff up and talk about something which (in the final version of the film) didn't happen. The octopus scene is included in the TV version of the movie.
(at around 1h 22 mins) When Andy tries to play the piano, she claims she can't tell if a note is "a-sharp or b-flat," which are one and the same. However, this was probably intentional to indicate how out of practice she is.
The whole point of the story revolves around the fact that the Goonies are losing their homes to the country club who intend to demolish the houses and build a golf course yet the town of Astoria is built into a steep hillside nobody in their right minds would build a golf course into a hillside as the golf balls would just roll away down the hill.
CORRECTION: While that is true that Astoria is built into a hillside, with proper construction and excavating, you could build the golf course you wanted to. Would just require a lot of flattening/dirt removal.
CORRECTION: While that is true that Astoria is built into a hillside, with proper construction and excavating, you could build the golf course you wanted to. Would just require a lot of flattening/dirt removal.
The incident with the plumbing makes the water dig a hole in the wall to reveal a secret entrance, however later in this new tunnel, the kids come across Chester Copperpot's skeleton. Since Copperpot had come that far, the wall should have already had its secret entrance opened. However, the basement with the (in-use) pipes was probably built after Copperpot went looking for the treasure.
(at around 7 mins) The balloon used for the automatic gate changes color from red to pink. The change was most likely a result of the red balloon stretching to its popping point and the stretching made it whiter, meaning it would be pink.
(at around 51 mins) When the pressure builds up and Troy is launched off the toilet by large amounts of water, you can easily see the platform he is sitting on and the pipe that pushes the platform up. Also, he is wearing red underwear on the toilet.
(at around 1h 45 mins) When Mikey's dad tears up the contract and tosses the pieces into the air, another extra bunch of pieces are thrown up in the same direction, a second after the initial throw.
(at around 49 mins) Chunk has a mole on his left upper lip. It's particularly obvious when he is reading about Chester Copperpot in the attic. But when he is thrown into the back of the black jeep, sees the dead body, and screams, the mole is on his right upper lip. It's Jeff Cohen's own mole, rather than a Hollywood mole, leading to the conclusion that the negative was flipped.
(at around 42 mins) When Data starts the printing press, you can see the plates say the number "100" and the word "hundred". But after the press feed the paper though, they come out as $50 dollar bills.
(at around 1h 35 mins) As One-Eyed Willy's ship leaves the cave, the rocks that fall into the water float.
Andi tells Brand that she was annoyed with Troy because 'he was adjusting the mirror to look down her shirt'. Andi wears a sweater throughout the movie, and in the scene where we see Brand riding Data's little sister's bike, we see Troy adjusting his car's mirror to look up her skirt, not down her shirt.
Kids are shown riding their bicycles from Astoria to Cannon Beach but these two towns are 40 miles apart from each other and would be incredibly difficult for kids to cover that distance with their small bicycles.
When the kids mess around with the plumbing, this causes shower knobs to get sucked into the walls and toilets to explode at the country club. Later on Sloth pushes a water pipe against the ceiling, and a car is heard crashing followed by a woman screaming. This seems to imply someone was driving a car around on the grounds of the country club.
(at around 8 mins) In the Goonie house, when Mouth, Mike, and Brandon tell Chunk all his made-up stories, Mouth tells him about when he said he ate his weight in pizza. Mouth says "Godfather's Pizza," but mouths "Pizza Hut." Pizza Hut refused to be mentioned in the movie, so the shot was overdubbed.
(at around 49 mins) When the people in the car reveal themselves to be the Fratellis, Jake Fratelli starts to sing a song in Italian. When the camera turns to show Chunk screaming, you can still hear Jake Fratelli singing, yet you see him in the mirror and his mouth is closed.
(at around 47 mins) When the Goonies first walk into the tunnel, Andy says "We've been walking forever. How far do we plan on going?" while mouthing something else.
(at around 27 mins) When Troy grabs Brandon on his bike and sends him hurtling off the road, Brandon yells out but his mouth is closed.
(at around 21 mins) When Sean Astin and Josh Brolin hug on the front porch, you can see director Richard Donner's trailer in the background.
(at around 1h 24 mins) When the kids are climbing the rope-ladder onto the ship, a crew-member's arm is cueing an event in middle-left of frame.
When Mikey picks up the line of string for the first booby trap, an adult hand pulls at the string first.
(at around 1h 23 mins) When the kids are riding down the slides to Willie's ship, working light bulbs are seen throughout the rides.
(at around 1h 2 mins) When Jake Fratelli takes his ice cream off Chunk, director Richard Donner can be heard giggling off-screen, when Chunk starts to cry.
(at around 1h 45 mins) The final scene looks out to sea, with the sun in the background. However, the scene is supposed to take place in the morning, not late afternoon (as it would have to be with the sun in that spot over the Pacific Ocean on the West Coast).
The story takes place in Astoria, Oregon, but the beach scenes are clearly shot north of Cannon Beach, with Ecola Head in the near background and Haystack Rock farther back. Cannon Beach is 30 miles from Astoria, too far for the kids to reach by bicycle to in the time given. Aside from mountain logging roads, the only road connecting the two towns is Highway 101, which carries too much traffic for kids to ride on. Astoria is also about 10 miles east of the coast.
(at around 42 mins) While the Goonies are looking at the printouts of the counterfeit money, Stef is seen in the background trying out the telephone. She hangs it up as if it is not working. Later Chunk uses the same phone to call the sheriff (at around 1h 11 mins).
It is not established how the doubloon ends up with Chunk so that the Fratellis are able to find it (but this was probably filmed and deleted because the screenplay indicates that Chunk retrieves the doubloon when the Goonies all fall to the floor after being frightened by Sloth).
(at around 40 mins) When the Goonies are arguing in the basement of the restaurant, Mikey (Sean Astin) calls Josh Brolin by his actual name (Josh) instead of "Brand," his character's name.
(at around 16 mins) During the attic scene, Data is seen looking at items he turns to Brand and says "don't touch it Josh" referring to Brand as Josh Brolin. Later on in the basement scene (at around 40 mins) Sean Astin picks up a poker and says to Brand "There is something buried under there Josh" yet again referring to Brand's actual actor name.
(at around 11 mins) When Mouth is translating in Spanish for Rosalita, he says, "La rapidez está en el cajón de abajo," which the captions translate as "speed is in the bottom drawer" referring to the drug methamphetamine. However, in Spanish, the word "rapidez" literally means velocity or speed, and it is not used to refer to the drug.
(at around 25 mins) When The Goonie Boys (minus Brand) ride their bikes to the shore, Mikey drops the map, jumps off his bike to go get it, and leaves his bike in the middle of the road.
(at around 43 mins) A paper the Goonies pick up in the basement of the restaurant has a headline that misspells "Fratellis" as "Fratelli's".