Corrected entry: At the end, it is Rosalita who saves the Goonies' homes from being sold, because she opens the marble bag to find all the precious jewels and runs over to everyone shouting "Don't sign." There's a huge problem with this though: it's already been established that Rosalita doesn't speak English.
Question: Wouldn't the plumbers who installed the pipes for the country club have had access to the cavern that didn't require them to face traps? Couldn't the kids have gotten out that way?
Answer: Once Mikey convinced everyone to stay down there and continue the treasure hunt, they stopped looking for a way out. There might have been another passage out of the cavern leading to such a door out, but we didn't see it from our angle and they just chose not to take it.
Answer: The pipes could have been there for decades, and the original entrance had been sealed or bulldozed (though the odds that the pipes never needed maintenance all that time are a little far-fetched).
Except that when they start banging on the pipes, it actually causes chaos at the country club that Troy is at.
Question: How did Brand knows where to find Mikey and The Goonies at the abandoned restaurant?
Answer: Brand didn't know specifically where the Goonies went, but he got on the bike and went searching. Viewers didn't get to see how many places Brand looked before he found them at the restaurant or how much time it took him, but he probably biked down the one road in town until he spotted their bikes and then looked nearby. The fact that Brand apparently found the Goonies within a short amount of time suggests that there were relatively few places that they could have gone, probably because they lived in a small town that was at least semi-rural. Other than old houses, there were only a few landmarks (including the restaurant and lighthouse). There may have been spots that kids tended to gravitate toward and Brand might have had a good idea as to where they most likely went.
It's a plot hole.
Correction: Every time I've ever seen this film she's speaking Spanish. Mouth struggles to understand her, and he finally translates it.
Krista
I literally watched this film last night, and it is totally untrue that she shouts "Don't sign" in English.