Stuck on this small htaccess code... any ideas?

Hi

I'm trying to accept urls like this:

http://www.mysite.com/file?http://www.somesite.com/pagewithvars.php?var=val

OR

http://www.mysite.com/file/?http://www.somesite.com/pagewithvars.php?var=val


The following htaccess code works, but anything after the .php is lost. Bolded
http://www.somesite.com/pagewithvars.php?var=val

RewriteRule ^file/(.*)$ get.php?file=$1 [NC,QSA]
RewriteRule ^file?(.*)$ get.php?file=$1 [NC,QSA]

Code (markup):

Any ideas appreciated

Thank you