It was in a file called "find_files.sh", and the command it generated was something like:
> find .... -exec ... {}\;
The problem is that there's no whitespace between the {} and \; and this is rejected by both GNU and BSD find.
It might've just been a mistake that someone made while putting the landing page together. But if it was generated, then how?? I can't imagine there are many (if any) instances of "{}\;" in the training data, since it's not a valid invocation of the find command...