1. The pirate ship was entirely real. All the shots were filmed in the ship. After the film, it was offered to anyone who would take it. No one wanted it, so the ship was scrapped.
2. Some of the crew members played extras in the film.
One cameraman played Mouth’s father.
Another played the dead man in the freezer.
And an assistant director plays one of the cops on the AV scooters on the beach at the end.
3. When the boys are sitting in the living room watching MTV, they weren’t actually watching the Cyndi Lauper “Good Enough” video, which was developed six months after filming wrapped up.
4. When the Fratelli brothers argue Anne Ramsey really slaps Robert Davi. She was told to hit him as hard as she could.
5. Jeff Cohen got the chicken pox after he got the role of Chunk.
He showed up to the set anyway, afraid that they would have replaced him otherwise.
6. Jennie Lew Tugend, assistant to director Richard Donner, has a small role as Data’s mom in the finale.
7. The cast was not allowed to see the pirate ship before the scene was shot.
When they did see it, some of the kids said “Holy shit!” The scene had to be re-shot without them cursing.
8. When Chunk and Sloth head down through the grate to follow the gang and the Fratellis, Sloth is wearing an Oakland Raiders T-Shirt.
John Matuszak, who played Sloth, was a former Oakland Raiders football player.
9. When rocks are falling from the cave ceiling, Jonathan Ke Quan (Data) screams “Holy S-H-I-T!”
He said he spelled the expletive because his mother made him promise not to use any bad language in the movie.
11. John Matuszak’s make-up took 5 hours to complete.
One of the eyes (which was out of place on the face) was mechanically operated off-screen by remote control. Someone would count down, and Matuszak would blink his other eye in synchronization. The cast was told not to get him wet in scenes outside of the pirate ship. Unfortunately, he got wet, delaying filming for an entire day.
12. According to Sean Astin, he was allowed to keep the treasure map used in the film. Several years later his mother discovered it, thought it was just a crinkled piece of paper, and threw it in the trash.
13. The name “Rube G” can be seen painted on the contraption that opens the yard gate for Chunk near the beginning of the movie.
This is in reference to Rube Goldberg, the Pulitzer Prize winning cartoonist who drew whimsical machines that achieved simple results in difficult ways.
14. The basis for the theater story was a real-life prank pulled by Executive Producer Steven Spielberg while growing up in Phoenix, AZ.
15. The bats were made of crumpled, black pieces of crepe paper that were shot out of an air cannon.
16. June 7th was officially declared “Goonies Day” by the Mayor of Astoria (where the movie was filmed) during the 25th Anniversary Celebration in 2010.
18. During filming, Martha Plimpton made a bet with director Richard Donner that she would stop biting her nails
Donner paid up several years later, while they were doing the DVD commentary.