Oy.

In an htaccess, I wanted to make some internal rewrites for a directory using mod_rewrite

It would have been better to use mod_alias for this, but you can't use Alias in a Directory/htaccess context, and I had no access to the vhost configuration.

Here's the first rewrite I tried:

RewriteRule ^some/path(.*) filesystem/directory$1

This worked and provided an internal rewrite for URLs like
- some/path/something
- some/path/