Script updated and gsub commented out (like a message earlier in the
thread):
-fstype=cifs,username=USER,password=PASS \
        "/C" "://xp0/C" \
        "/ADMIN$" "://xp0/ADMIN$" \
        "/C$" "://xp0/C$"

cd /smb/xp0/C$  gives
cd: no such file or directory: /smb/xp0/C$

something is really busted now since I can't even cd /smb/xp0/C either.
I don't understand why the debug log contains what looks like parts of
the script as the output since running the script manually seems to have
perfectly clean output
    

Because the script file is not executable now it is treating it as a
file map not a program map.