Passing an argument to a node causes 404
There are modules to accept subpath aliases.

If you're on Drupal 6 then look into the subpath_alias module. 

Drupal 7 has subpathauto which does the same thing.

What they do is expand Drupal's path matching to work with subpaths, so no extra aliases are added. I've used it in the past when embedding views within nodes and it worked a treat.

So if you have node/4 aliased to path/test then it will recognise path/test/argument as node/4/argument